Browse 3259 problem solutions with detailed explanations
| Solution | Tags | Difficulty | Remark |
|---|---|---|---|
| 1. Two Sum | Array Hash Table | Easy | |
| 2. Add Two Numbers | Recursion Linked List Math | Medium | |
| 3. Longest Substring Without Repeating Characters | Hash Table String Sliding Window | Medium | |
| 4. Median of Two Sorted Arrays | Array Binary Search Divide and Conquer | Hard | |
| 5. Longest Palindromic Substring | Two Pointers String Dynamic Programming | Medium | |
| 6. Zigzag Conversion | String | Medium | |
| 7. Reverse Integer | Math | Medium | |
| 8. String to Integer (atoi) | String | Medium | |
| 9. Palindrome Number | Math | Easy | |
| 10. Regular Expression Matching | Recursion String Dynamic Programming | Hard | |
| 11. Container With Most Water | Greedy Array Two Pointers | Medium | |
| 12. Integer to Roman | Hash Table Math String | Medium | |
| 13. Roman to Integer | Hash Table Math String | Easy | |
| 14. Longest Common Prefix | Trie Array String | Easy | |
| 15. 3Sum | Array Two Pointers Sorting | Medium | |
| 16. 3Sum Closest | Array Two Pointers Sorting | Medium | |
| 17. Letter Combinations of a Phone Number | Hash Table String Backtracking | Medium | |
| 18. 4Sum | Array Two Pointers Sorting | Medium | |
| 19. Remove Nth Node From End of List | Linked List Two Pointers | Medium | |
| 20. Valid Parentheses | Stack String | Easy | |
| 21. Merge Two Sorted Lists | Recursion Linked List | Easy | |
| 22. Generate Parentheses | String Dynamic Programming Backtracking | Medium | |
| 23. Merge k Sorted Lists | Linked List Divide and Conquer Heap (Priority Queue) Merge Sort | Hard | |
| 24. Swap Nodes in Pairs | Recursion Linked List | Medium | |
| 25. Reverse Nodes in k-Group | Recursion Linked List | Hard | |
| 26. Remove Duplicates from Sorted Array | Array Two Pointers | Easy | |
| 27. Remove Element | Array Two Pointers | Easy | |
| 28. Find the Index of the First Occurrence in a String | Two Pointers String String Matching | Easy | |
| 29. Divide Two Integers | Bit Manipulation Math | Medium | |
| 30. Substring with Concatenation of All Words | Hash Table String Sliding Window | Hard | |
| 31. Next Permutation | Array Two Pointers | Medium | |
| 32. Longest Valid Parentheses | Stack String Dynamic Programming | Hard | |
| 33. Search in Rotated Sorted Array | Array Binary Search | Medium | |
| 34. Find First and Last Position of Element in Sorted Array | Array Binary Search | Medium | |
| 35. Search Insert Position | Array Binary Search | Easy | |
| 36. Valid Sudoku | Array Hash Table Matrix | Medium | |
| 37. Sudoku Solver | Array Hash Table Backtracking Matrix | Hard | |
| 38. Count and Say | String | Medium | |
| 39. Combination Sum | Array Backtracking | Medium | |
| 40. Combination Sum II | Array Backtracking | Medium | |
| 41. First Missing Positive | Array Hash Table | Hard | |
| 42. Trapping Rain Water | Stack Array Two Pointers Dynamic Programming Monotonic Stack | Hard | |
| 43. Multiply Strings | Math String Simulation | Medium | |
| 44. Wildcard Matching | Greedy Recursion String Dynamic Programming | Hard | |
| 45. Jump Game II | Greedy Array Dynamic Programming | Medium | |
| 46. Permutations | Array Backtracking | Medium | |
| 47. Permutations II | Array Backtracking Sorting | Medium | |
| 48. Rotate Image | Array Math Matrix | Medium | |
| 49. Group Anagrams | Array Hash Table String Sorting | Medium | |
| 50. Pow(x, n) | Recursion Math | Medium | |
| 51. N-Queens | Array Backtracking | Hard | |
| 52. N-Queens II | Backtracking | Hard | |
| 53. Maximum Subarray | Array Divide and Conquer Dynamic Programming | Medium | |
| 54. Spiral Matrix | Array Matrix Simulation | Medium | |
| 55. Jump Game | Greedy Array Dynamic Programming | Medium | |
| 56. Merge Intervals | Array Sorting | Medium | |
| 57. Insert Interval | Array | Medium | |
| 58. Length of Last Word | String | Easy | |
| 59. Spiral Matrix II | Array Matrix Simulation | Medium | |
| 60. Permutation Sequence | Recursion Math | Hard | |
| 61. Rotate List | Linked List Two Pointers | Medium | |
| 62. Unique Paths | Math Dynamic Programming Combinatorics | Medium | |
| 63. Unique Paths II | Array Dynamic Programming Matrix | Medium | |
| 64. Minimum Path Sum | Array Dynamic Programming Matrix | Medium | |
| 65. Valid Number | String | Hard | |
| 66. Plus One | Array Math | Easy | |
| 67. Add Binary | Bit Manipulation Math String Simulation | Easy | |
| 68. Text Justification | Array String Simulation | Hard | |
| 69. Sqrt(x) | Math Binary Search | Easy | |
| 70. Climbing Stairs | Memoization Math Dynamic Programming | Easy | |
| 71. Simplify Path | Stack String | Medium | |
| 72. Edit Distance | String Dynamic Programming | Medium | |
| 73. Set Matrix Zeroes | Array Hash Table Matrix | Medium | |
| 74. Search a 2D Matrix | Array Binary Search Matrix | Medium | |
| 75. Sort Colors | Array Two Pointers Sorting | Medium | |
| 76. Minimum Window Substring | Hash Table String Sliding Window | Hard | |
| 77. Combinations | Backtracking | Medium | |
| 78. Subsets | Bit Manipulation Array Backtracking | Medium | |
| 79. Word Search | Depth-First Search Array String Backtracking Matrix | Medium | |
| 80. Remove Duplicates from Sorted Array II | Array Two Pointers | Medium | |
| 81. Search in Rotated Sorted Array II | Array Binary Search | Medium | |
| 82. Remove Duplicates from Sorted List II | Linked List Two Pointers | Medium | |
| 83. Remove Duplicates from Sorted List | Linked List | Easy | |
| 84. Largest Rectangle in Histogram | Stack Array Monotonic Stack | Hard | |
| 85. Maximal Rectangle | Stack Array Dynamic Programming Matrix Monotonic Stack | Hard | |
| 86. Partition List | Linked List Two Pointers | Medium | |
| 87. Scramble String | String Dynamic Programming | Hard | |
| 88. Merge Sorted Array | Array Two Pointers Sorting | Easy | |
| 89. Gray Code | Bit Manipulation Math Backtracking | Medium | |
| 90. Subsets II | Bit Manipulation Array Backtracking | Medium | |
| 91. Decode Ways | String Dynamic Programming | Medium | |
| 92. Reverse Linked List II | Linked List | Medium | |
| 93. Restore IP Addresses | String Backtracking | Medium | |
| 94. Binary Tree Inorder Traversal | Stack Tree Depth-First Search Binary Tree | Easy | |
| 95. Unique Binary Search Trees II | Tree Binary Search Tree Dynamic Programming Backtracking Binary Tree | Medium | |
| 96. Unique Binary Search Trees | Tree Binary Search Tree Math Dynamic Programming Binary Tree | Medium | |
| 97. Interleaving String | String Dynamic Programming | Medium | |
| 98. Validate Binary Search Tree | Tree Depth-First Search Binary Search Tree Binary Tree | Medium | |
| 99. Recover Binary Search Tree | Tree Depth-First Search Binary Search Tree Binary Tree | Medium | |
| 100. Same Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Easy | |
| 101. Symmetric Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Easy | |
| 102. Binary Tree Level Order Traversal | Tree Breadth-First Search Binary Tree | Medium | |
| 103. Binary Tree Zigzag Level Order Traversal | Tree Breadth-First Search Binary Tree | Medium | |
| 104. Maximum Depth of Binary Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Easy | |
| 105. Construct Binary Tree from Preorder and Inorder Traversal | Tree Array Hash Table Divide and Conquer Binary Tree | Medium | |
| 106. Construct Binary Tree from Inorder and Postorder Traversal | Tree Array Hash Table Divide and Conquer Binary Tree | Medium | |
| 107. Binary Tree Level Order Traversal II | Tree Breadth-First Search Binary Tree | Medium | |
| 108. Convert Sorted Array to Binary Search Tree | Tree Binary Search Tree Array Divide and Conquer Binary Tree | Easy | |
| 109. Convert Sorted List to Binary Search Tree | Tree Binary Search Tree Linked List Divide and Conquer Binary Tree | Medium | |
| 110. Balanced Binary Tree | Tree Depth-First Search Binary Tree | Easy | |
| 111. Minimum Depth of Binary Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Easy | |
| 112. Path Sum | Tree Depth-First Search Breadth-First Search Binary Tree | Easy | |
| 113. Path Sum II | Tree Depth-First Search Backtracking Binary Tree | Medium | |
| 114. Flatten Binary Tree to Linked List | Stack Tree Depth-First Search Linked List Binary Tree | Medium | |
| 115. Distinct Subsequences | String Dynamic Programming | Hard | |
| 116. Populating Next Right Pointers in Each Node | Tree Depth-First Search Breadth-First Search Linked List Binary Tree | Medium | |
| 117. Populating Next Right Pointers in Each Node II | Tree Depth-First Search Breadth-First Search Linked List Binary Tree | Medium | |
| 118. Pascal's Triangle | Array Dynamic Programming | Easy | |
| 119. Pascal's Triangle II | Array Dynamic Programming | Easy | |
| 120. Triangle | Array Dynamic Programming | Medium | |
| 121. Best Time to Buy and Sell Stock | Array Dynamic Programming | Easy | |
| 122. Best Time to Buy and Sell Stock II | Greedy Array Dynamic Programming | Medium | |
| 123. Best Time to Buy and Sell Stock III | Array Dynamic Programming | Hard | |
| 124. Binary Tree Maximum Path Sum | Tree Depth-First Search Dynamic Programming Binary Tree | Hard | |
| 125. Valid Palindrome | Two Pointers String | Easy | |
| 126. Word Ladder II | Breadth-First Search Hash Table String Backtracking | Hard | |
| 127. Word Ladder | Breadth-First Search Hash Table String | Hard | |
| 128. Longest Consecutive Sequence | Union Find Array Hash Table | Medium | |
| 129. Sum Root to Leaf Numbers | Tree Depth-First Search Binary Tree | Medium | |
| 130. Surrounded Regions | Depth-First Search Breadth-First Search Union Find Array Matrix | Medium | |
| 131. Palindrome Partitioning | String Dynamic Programming Backtracking | Medium | |
| 132. Palindrome Partitioning II | String Dynamic Programming | Hard | |
| 133. Clone Graph | Depth-First Search Breadth-First Search Graph Hash Table | Medium | |
| 134. Gas Station | Greedy Array | Medium | |
| 135. Candy | Greedy Array | Hard | |
| 136. Single Number | Bit Manipulation Array | Easy | |
| 137. Single Number II | Bit Manipulation Array | Medium | |
| 138. Copy List with Random Pointer | Hash Table Linked List | Medium | |
| 139. Word Break | Trie Memoization Array Hash Table String Dynamic Programming | Medium | |
| 140. Word Break II | Trie Memoization Array Hash Table String Dynamic Programming Backtracking | Hard | |
| 141. Linked List Cycle | Hash Table Linked List Two Pointers | Easy | |
| 142. Linked List Cycle II | Hash Table Linked List Two Pointers | Medium | |
| 143. Reorder List | Stack Recursion Linked List Two Pointers | Medium | |
| 144. Binary Tree Preorder Traversal | Stack Tree Depth-First Search Binary Tree | Easy | |
| 145. Binary Tree Postorder Traversal | Stack Tree Depth-First Search Binary Tree | Easy | |
| 146. LRU Cache | Design Hash Table Linked List Doubly-Linked List | Medium | |
| 147. Insertion Sort List | Linked List Sorting | Medium | |
| 148. Sort List | Linked List Two Pointers Divide and Conquer Sorting Merge Sort | Medium | |
| 149. Max Points on a Line | Geometry Array Hash Table Math | Hard | |
| 150. Evaluate Reverse Polish Notation | Stack Array Math | Medium | |
| 151. Reverse Words in a String | Two Pointers String | Medium | |
| 152. Maximum Product Subarray | Array Dynamic Programming | Medium | |
| 153. Find Minimum in Rotated Sorted Array | Array Binary Search | Medium | |
| 154. Find Minimum in Rotated Sorted Array II | Array Binary Search | Hard | |
| 155. Min Stack | Stack Design | Medium | |
| 156. Binary Tree Upside Down | Tree Depth-First Search Binary Tree | Medium | |
| 157. Read N Characters Given Read4 | Array Interactive Simulation | Easy | |
| 158. Read N Characters Given read4 II - Call Multiple Times | Array Interactive Simulation | Hard | |
| 159. Longest Substring with At Most Two Distinct Characters | Hash Table String Sliding Window | Medium | |
| 160. Intersection of Two Linked Lists | Hash Table Linked List Two Pointers | Easy | |
| 161. One Edit Distance | Two Pointers String | Medium | |
| 162. Find Peak Element | Array Binary Search | Medium | |
| 163. Missing Ranges | Array | Easy | |
| 164. Maximum Gap | Array Bucket Sort Radix Sort Sorting | Medium | |
| 165. Compare Version Numbers | Two Pointers String | Medium | |
| 166. Fraction to Recurring Decimal | Hash Table Math String | Medium | |
| 167. Two Sum II - Input Array Is Sorted | Array Two Pointers Binary Search | Medium | |
| 168. Excel Sheet Column Title | Math String | Easy | |
| 169. Majority Element | Array Hash Table Divide and Conquer Counting Sorting | Easy | |
| 170. Two Sum III - Data structure design | Design Array Hash Table Two Pointers Data Stream | Easy | |
| 171. Excel Sheet Column Number | Math String | Easy | |
| 172. Factorial Trailing Zeroes | Math | Medium | |
| 173. Binary Search Tree Iterator | Stack Tree Design Binary Search Tree Binary Tree Iterator | Medium | |
| 174. Dungeon Game | Array Dynamic Programming Matrix | Hard | |
| 179. Largest Number | Greedy Array String Sorting | Medium | |
| 186. Reverse Words in a String II | Two Pointers String | Medium | |
| 187. Repeated DNA Sequences | Bit Manipulation Hash Table String Sliding Window Hash Function Rolling Hash | Medium | |
| 188. Best Time to Buy and Sell Stock IV | Array Dynamic Programming | Hard | |
| 189. Rotate Array | Array Math Two Pointers | Medium | |
| 190. Reverse Bits | Bit Manipulation Divide and Conquer | Easy | |
| 191. Number of 1 Bits | Bit Manipulation Divide and Conquer | Easy | |
| 198. House Robber | Array Dynamic Programming | Medium | |
| 199. Binary Tree Right Side View | Tree Depth-First Search Breadth-First Search Binary Tree | Medium | |
| 200. Number of Islands | Depth-First Search Breadth-First Search Union Find Array Matrix | Medium | |
| 201. Bitwise AND of Numbers Range | Bit Manipulation | Medium | |
| 202. Happy Number | Hash Table Math Two Pointers | Easy | |
| 203. Remove Linked List Elements | Recursion Linked List | Easy | |
| 204. Count Primes | Array Math Enumeration Number Theory | Medium | |
| 205. Isomorphic Strings | Hash Table String | Easy | |
| 206. Reverse Linked List | Recursion Linked List | Easy | |
| 207. Course Schedule | Depth-First Search Breadth-First Search Graph Topological Sort | Medium | |
| 208. Implement Trie (Prefix Tree) | Design Trie Hash Table String | Medium | |
| 209. Minimum Size Subarray Sum | Array Binary Search Prefix Sum Sliding Window | Medium | |
| 210. Course Schedule II | Depth-First Search Breadth-First Search Graph Topological Sort | Medium | |
| 211. Design Add and Search Words Data Structure | Depth-First Search Design Trie String | Medium | |
| 212. Word Search II | Trie Array String Backtracking Matrix | Hard | |
| 213. House Robber II | Array Dynamic Programming | Medium | |
| 214. Shortest Palindrome | String String Matching Hash Function Rolling Hash | Hard | |
| 215. Kth Largest Element in an Array | Array Divide and Conquer Quickselect Sorting Heap (Priority Queue) | Medium | |
| 216. Combination Sum III | Array Backtracking | Medium | |
| 217. Contains Duplicate | Array Hash Table Sorting | Easy | |
| 218. The Skyline Problem | Binary Indexed Tree Segment Tree Array Divide and Conquer Ordered Set Line Sweep Heap (Priority Queue) | Hard | |
| 219. Contains Duplicate II | Array Hash Table Sliding Window | Easy | |
| 220. Contains Duplicate III | Array Bucket Sort Ordered Set Sorting Sliding Window | Hard | |
| 221. Maximal Square | Array Dynamic Programming Matrix | Medium | |
| 222. Count Complete Tree Nodes | Bit Manipulation Tree Binary Search Binary Tree | Easy | |
| 223. Rectangle Area | Geometry Math | Medium | |
| 224. Basic Calculator | Stack Recursion Math String | Hard | |
| 225. Implement Stack using Queues | Stack Design Queue | Easy | |
| 226. Invert Binary Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Easy | |
| 227. Basic Calculator II | Stack Math String | Medium | |
| 228. Summary Ranges | Array | Easy | |
| 229. Majority Element II | Array Hash Table Counting Sorting | Medium | |
| 230. Kth Smallest Element in a BST | Tree Depth-First Search Binary Search Tree Binary Tree | Medium | |
| 231. Power of Two | Bit Manipulation Recursion Math | Easy | |
| 232. Implement Queue using Stacks | Stack Design Queue | Easy | |
| 233. Number of Digit One | Recursion Math Dynamic Programming | Hard | |
| 234. Palindrome Linked List | Stack Recursion Linked List Two Pointers | Easy | |
| 235. Lowest Common Ancestor of a Binary Search Tree | Tree Depth-First Search Binary Search Tree Binary Tree | Medium | |
| 236. Lowest Common Ancestor of a Binary Tree | Tree Depth-First Search Binary Tree | Medium | |
| 237. Delete Node in a Linked List | Linked List | Medium | |
| 238. Product of Array Except Self | Array Prefix Sum | Medium | |
| 239. Sliding Window Maximum | Queue Array Sliding Window Monotonic Queue Heap (Priority Queue) | Hard | |
| 240. Search a 2D Matrix II | Array Binary Search Divide and Conquer Matrix | Medium | |
| 241. Different Ways to Add Parentheses | Recursion Memoization Math String Dynamic Programming | Medium | |
| 242. Valid Anagram | Hash Table String Sorting | Easy | |
| 243. Shortest Word Distance | Array String | Easy | |
| 244. Shortest Word Distance II | Design Array Hash Table Two Pointers String | Medium | |
| 245. Shortest Word Distance III | Array String | Medium | |
| 246. Strobogrammatic Number | Hash Table Two Pointers String | Easy | |
| 247. Strobogrammatic Number II | Recursion Array String | Medium | |
| 248. Strobogrammatic Number III | Recursion Array String | Hard | |
| 249. Group Shifted Strings | Array Hash Table String | Medium | |
| 250. Count Univalue Subtrees | Tree Depth-First Search Binary Tree | Medium | |
| 251. Flatten 2D Vector | Design Array Two Pointers Iterator | Medium | |
| 252. Meeting Rooms | Array Sorting | Easy | |
| 253. Meeting Rooms II | Greedy Array Two Pointers Prefix Sum Sorting Heap (Priority Queue) | Medium | |
| 254. Factor Combinations | Backtracking | Medium | |
| 255. Verify Preorder Sequence in Binary Search Tree | Stack Tree Binary Search Tree Recursion Array Binary Tree Monotonic Stack | Medium | |
| 256. Paint House | Array Dynamic Programming | Medium | |
| 257. Binary Tree Paths | Tree Depth-First Search String Backtracking Binary Tree | Easy | |
| 258. Add Digits | Math Number Theory Simulation | Easy | |
| 259. 3Sum Smaller | Array Two Pointers Binary Search Sorting | Medium | |
| 260. Single Number III | Bit Manipulation Array | Medium | |
| 261. Graph Valid Tree | Depth-First Search Breadth-First Search Union Find Graph | Medium | |
| 263. Ugly Number | Math | Easy | |
| 264. Ugly Number II | Hash Table Math Dynamic Programming Heap (Priority Queue) | Medium | |
| 265. Paint House II | Array Dynamic Programming | Hard | |
| 266. Palindrome Permutation | Bit Manipulation Hash Table String | Easy | |
| 267. Palindrome Permutation II | Hash Table String Backtracking | Medium | |
| 268. Missing Number | Bit Manipulation Array Hash Table Math Binary Search Sorting | Easy | |
| 269. Alien Dictionary | Depth-First Search Breadth-First Search Graph Topological Sort Array String | Hard | |
| 270. Closest Binary Search Tree Value | Tree Depth-First Search Binary Search Tree Binary Search Binary Tree | Easy | |
| 271. Encode and Decode Strings | Design Array String | Medium | |
| 272. Closest Binary Search Tree Value II | Stack Tree Depth-First Search Binary Search Tree Two Pointers Binary Tree Heap (Priority Queue) | Hard | |
| 273. Integer to English Words | Recursion Math String | Hard | |
| 274. H-Index | Array Counting Sort Sorting | Medium | |
| 275. H-Index II | Array Binary Search | Medium | |
| 276. Paint Fence | Dynamic Programming | Medium | |
| 277. Find the Celebrity | Graph Two Pointers Interactive | Medium | |
| 278. First Bad Version | Binary Search Interactive | Easy | |
| 279. Perfect Squares | Breadth-First Search Math Dynamic Programming | Medium | |
| 280. Wiggle Sort | Greedy Array Sorting | Medium | |
| 281. Zigzag Iterator | Design Queue Array Iterator | Medium | |
| 282. Expression Add Operators | Math String Backtracking | Hard | |
| 283. Move Zeroes | Array Two Pointers | Easy | |
| 284. Peeking Iterator | Design Array Iterator | Medium | |
| 285. Inorder Successor in BST | Tree Depth-First Search Binary Search Tree Binary Tree | Medium | |
| 286. Walls and Gates | Breadth-First Search Array Matrix | Medium | |
| 287. Find the Duplicate Number | Bit Manipulation Array Two Pointers Binary Search | Medium | |
| 288. Unique Word Abbreviation | Design Array Hash Table String | Medium | |
| 289. Game of Life | Array Matrix Simulation | Medium | |
| 290. Word Pattern | Hash Table String | Easy | |
| 291. Word Pattern II | Hash Table String Backtracking | Medium | |
| 292. Nim Game | Brainteaser Math Game Theory | Easy | |
| 293. Flip Game | String | Easy | |
| 294. Flip Game II | Memoization Math Dynamic Programming Backtracking Game Theory | Medium | |
| 295. Find Median from Data Stream | Design Two Pointers Data Stream Sorting Heap (Priority Queue) | Hard | |
| 296. Best Meeting Point | Array Math Matrix Sorting | Hard | |
| 297. Serialize and Deserialize Binary Tree | Tree Depth-First Search Breadth-First Search Design String Binary Tree | Hard | |
| 298. Binary Tree Longest Consecutive Sequence | Tree Depth-First Search Binary Tree | Medium | |
| 299. Bulls and Cows | Hash Table String Counting | Medium | |
| 300. Longest Increasing Subsequence | Array Binary Search Dynamic Programming | Medium | |
| 301. Remove Invalid Parentheses | Breadth-First Search String Backtracking | Hard | |
| 302. Smallest Rectangle Enclosing Black Pixels | Depth-First Search Breadth-First Search Array Binary Search Matrix | Hard | |
| 303. Range Sum Query - Immutable | Design Array Prefix Sum | Easy | |
| 304. Range Sum Query 2D - Immutable | Design Array Matrix Prefix Sum | Medium | |
| 305. Number of Islands II | Union Find Array Hash Table | Hard | |
| 306. Additive Number | String Backtracking | Medium | |
| 307. Range Sum Query - Mutable | Design Binary Indexed Tree Segment Tree Array Divide and Conquer | Medium | |
| 308. Range Sum Query 2D - Mutable | Design Binary Indexed Tree Segment Tree Array Matrix | Medium | |
| 309. Best Time to Buy and Sell Stock with Cooldown | Array Dynamic Programming | Medium | |
| 310. Minimum Height Trees | Depth-First Search Breadth-First Search Graph Topological Sort | Medium | |
| 311. Sparse Matrix Multiplication | Array Hash Table Matrix | Medium | |
| 312. Burst Balloons | Array Dynamic Programming | Hard | |
| 313. Super Ugly Number | Array Math Dynamic Programming | Medium | |
| 314. Binary Tree Vertical Order Traversal | Tree Depth-First Search Breadth-First Search Hash Table Binary Tree Sorting | Medium | |
| 315. Count of Smaller Numbers After Self | Binary Indexed Tree Segment Tree Array Binary Search Divide and Conquer Ordered Set Merge Sort | Hard | |
| 316. Remove Duplicate Letters | Stack Greedy String Monotonic Stack | Medium | |
| 317. Shortest Distance from All Buildings | Breadth-First Search Array Matrix | Hard | |
| 318. Maximum Product of Word Lengths | Bit Manipulation Array String | Medium | |
| 319. Bulb Switcher | Brainteaser Math | Medium | |
| 320. Generalized Abbreviation | Bit Manipulation String Backtracking | Medium | |
| 321. Create Maximum Number | Stack Greedy Array Two Pointers Monotonic Stack | Hard | |
| 322. Coin Change | Breadth-First Search Array Dynamic Programming | Medium | |
| 323. Number of Connected Components in an Undirected Graph | Depth-First Search Breadth-First Search Union Find Graph | Medium | |
| 324. Wiggle Sort II | Greedy Array Divide and Conquer Quickselect Sorting | Medium | |
| 325. Maximum Size Subarray Sum Equals k | Array Hash Table Prefix Sum | Medium | |
| 326. Power of Three | Recursion Math | Easy | |
| 327. Count of Range Sum | Binary Indexed Tree Segment Tree Array Binary Search Divide and Conquer Ordered Set Merge Sort | Hard | |
| 328. Odd Even Linked List | Linked List | Medium | |
| 329. Longest Increasing Path in a Matrix | Depth-First Search Breadth-First Search Graph Topological Sort Memoization Array Dynamic Programming Matrix | Hard | |
| 330. Patching Array | Greedy Array | Hard | |
| 331. Verify Preorder Serialization of a Binary Tree | Stack Tree String Binary Tree | Medium | |
| 332. Reconstruct Itinerary | Depth-First Search Graph Eulerian Circuit | Hard | |
| 333. Largest BST Subtree | Tree Depth-First Search Binary Search Tree Dynamic Programming Binary Tree | Medium | |
| 334. Increasing Triplet Subsequence | Greedy Array | Medium | |
| 335. Self Crossing | Geometry Array Math | Hard | |
| 336. Palindrome Pairs | Trie Array Hash Table String | Hard | |
| 337. House Robber III | Tree Depth-First Search Dynamic Programming Binary Tree | Medium | |
| 338. Counting Bits | Bit Manipulation Dynamic Programming | Easy | |
| 339. Nested List Weight Sum | Depth-First Search Breadth-First Search | Medium | |
| 340. Longest Substring with At Most K Distinct Characters | Hash Table String Sliding Window | Medium | |
| 341. Flatten Nested List Iterator | Stack Tree Depth-First Search Design Queue Iterator | Medium | |
| 342. Power of Four | Bit Manipulation Recursion Math | Easy | |
| 343. Integer Break | Math Dynamic Programming | Medium | |
| 344. Reverse String | Two Pointers String | Easy | |
| 345. Reverse Vowels of a String | Two Pointers String | Easy | |
| 346. Moving Average from Data Stream | Design Queue Array Data Stream | Easy | |
| 347. Top K Frequent Elements | Array Hash Table Divide and Conquer Bucket Sort Counting Quickselect Sorting Heap (Priority Queue) | Medium | |
| 348. Design Tic-Tac-Toe | Design Array Hash Table Matrix Simulation | Medium | |
| 349. Intersection of Two Arrays | Array Hash Table Two Pointers Binary Search Sorting | Easy | |
| 350. Intersection of Two Arrays II | Array Hash Table Two Pointers Binary Search Sorting | Easy | |
| 351. Android Unlock Patterns | Bit Manipulation Dynamic Programming Backtracking Bitmask | Medium | |
| 352. Data Stream as Disjoint Intervals | Design Binary Search Ordered Set | Hard | |
| 353. Design Snake Game | Design Queue Array Hash Table Simulation | Medium | |
| 354. Russian Doll Envelopes | Array Binary Search Dynamic Programming Sorting | Hard | |
| 355. Design Twitter | Design Hash Table Linked List Heap (Priority Queue) | Medium | |
| 356. Line Reflection | Array Hash Table Math | Medium | |
| 357. Count Numbers with Unique Digits | Math Dynamic Programming Backtracking | Medium | |
| 358. Rearrange String k Distance Apart | Greedy Hash Table String Counting Sorting Heap (Priority Queue) | Hard | |
| 359. Logger Rate Limiter | Design Hash Table Data Stream | Easy | |
| 360. Sort Transformed Array | Array Math Two Pointers Sorting | Medium | |
| 361. Bomb Enemy | Array Dynamic Programming Matrix | Medium | |
| 362. Design Hit Counter | Design Queue Array Binary Search Data Stream | Medium | |
| 363. Max Sum of Rectangle No Larger Than K | Array Binary Search Matrix Ordered Set Prefix Sum | Hard | |
| 364. Nested List Weight Sum II | Stack Depth-First Search Breadth-First Search | Medium | |
| 365. Water and Jug Problem | Depth-First Search Breadth-First Search Math | Medium | |
| 366. Find Leaves of Binary Tree | Tree Depth-First Search Binary Tree | Medium | |
| 367. Valid Perfect Square | Math Binary Search | Easy | |
| 368. Largest Divisible Subset | Array Math Dynamic Programming Sorting | Medium | |
| 369. Plus One Linked List | Linked List Math | Medium | |
| 370. Range Addition | Array Prefix Sum | Medium | |
| 371. Sum of Two Integers | Bit Manipulation Math | Medium | |
| 372. Super Pow | Math Divide and Conquer | Medium | |
| 373. Find K Pairs with Smallest Sums | Array Heap (Priority Queue) | Medium | |
| 374. Guess Number Higher or Lower | Binary Search Interactive | Easy | |
| 375. Guess Number Higher or Lower II | Math Dynamic Programming Game Theory | Medium | |
| 376. Wiggle Subsequence | Greedy Array Dynamic Programming | Medium | |
| 377. Combination Sum IV | Array Dynamic Programming | Medium | |
| 378. Kth Smallest Element in a Sorted Matrix | Array Binary Search Matrix Sorting Heap (Priority Queue) | Medium | |
| 379. Design Phone Directory | Design Queue Array Hash Table Linked List | Medium | |
| 380. Insert Delete GetRandom O(1) | Design Array Hash Table Math Randomized | Medium | |
| 381. Insert Delete GetRandom O(1) - Duplicates allowed | Design Array Hash Table Math Randomized | Hard | |
| 382. Linked List Random Node | Reservoir Sampling Linked List Math Randomized | Medium | |
| 383. Ransom Note | Hash Table String Counting | Easy | |
| 384. Shuffle an Array | Design Array Math Randomized | Medium | |
| 385. Mini Parser | Stack Depth-First Search String | Medium | |
| 386. Lexicographical Numbers | Depth-First Search Trie | Medium | |
| 387. First Unique Character in a String | Queue Hash Table String Counting | Easy | |
| 388. Longest Absolute File Path | Stack Depth-First Search String | Medium | |
| 389. Find the Difference | Bit Manipulation Hash Table String Sorting | Easy | |
| 390. Elimination Game | Recursion Math | Medium | |
| 391. Perfect Rectangle | Geometry Array Hash Table Math Line Sweep | Hard | |
| 392. Is Subsequence | Two Pointers String Dynamic Programming | Easy | |
| 393. UTF-8 Validation | Bit Manipulation Array | Medium | |
| 394. Decode String | Stack Recursion String | Medium | |
| 395. Longest Substring with At Least K Repeating Characters | Hash Table String Divide and Conquer Sliding Window | Medium | |
| 396. Rotate Function | Array Math Dynamic Programming | Medium | |
| 397. Integer Replacement | Greedy Bit Manipulation Memoization Dynamic Programming | Medium | |
| 398. Random Pick Index | Reservoir Sampling Hash Table Math Randomized | Medium | |
| 399. Evaluate Division | Depth-First Search Breadth-First Search Union Find Graph Array String Shortest Path | Medium | |
| 400. Nth Digit | Math Binary Search | Medium | |
| 401. Binary Watch | Bit Manipulation Backtracking | Easy | |
| 402. Remove K Digits | Stack Greedy String Monotonic Stack | Medium | |
| 403. Frog Jump | Array Dynamic Programming | Hard | |
| 404. Sum of Left Leaves | Tree Depth-First Search Breadth-First Search Binary Tree | Easy | |
| 405. Convert a Number to Hexadecimal | Bit Manipulation Math String | Easy | |
| 406. Queue Reconstruction by Height | Binary Indexed Tree Segment Tree Array Sorting | Medium | |
| 407. Trapping Rain Water II | Breadth-First Search Array Matrix Heap (Priority Queue) | Hard | |
| 408. Valid Word Abbreviation | Two Pointers String | Easy | |
| 409. Longest Palindrome | Greedy Hash Table String | Easy | |
| 410. Split Array Largest Sum | Greedy Array Binary Search Dynamic Programming Prefix Sum | Hard | |
| 411. Minimum Unique Word Abbreviation | Bit Manipulation Array String Backtracking | Hard | |
| 412. Fizz Buzz | Math String Simulation | Easy | |
| 413. Arithmetic Slices | Array Dynamic Programming Sliding Window | Medium | |
| 414. Third Maximum Number | Array Sorting | Easy | |
| 415. Add Strings | Math String Simulation | Easy | |
| 416. Partition Equal Subset Sum | Array Dynamic Programming | Medium | |
| 417. Pacific Atlantic Water Flow | Depth-First Search Breadth-First Search Array Matrix | Medium | |
| 418. Sentence Screen Fitting | Array String Dynamic Programming | Medium | |
| 419. Battleships in a Board | Depth-First Search Array Matrix | Medium | |
| 420. Strong Password Checker | Greedy String Heap (Priority Queue) | Hard | |
| 421. Maximum XOR of Two Numbers in an Array | Bit Manipulation Trie Array Hash Table | Medium | |
| 422. Valid Word Square | Array Matrix | Easy | |
| 423. Reconstruct Original Digits from English | Hash Table Math String | Medium | |
| 424. Longest Repeating Character Replacement | Hash Table String Sliding Window | Medium | |
| 425. Word Squares | Trie Array String Backtracking | Hard | |
| 426. Convert Binary Search Tree to Sorted Doubly Linked List | Stack Tree Depth-First Search Binary Search Tree Linked List Binary Tree Doubly-Linked List | Medium | |
| 427. Construct Quad Tree | Tree Array Divide and Conquer Matrix | Medium | |
| 428. Serialize and Deserialize N-ary Tree | Tree Depth-First Search Breadth-First Search String | Hard | |
| 429. N-ary Tree Level Order Traversal | Tree Breadth-First Search | Medium | |
| 430. Flatten a Multilevel Doubly Linked List | Depth-First Search Linked List Doubly-Linked List | Medium | |
| 431. Encode N-ary Tree to Binary Tree | Tree Depth-First Search Breadth-First Search Design Binary Tree | Hard | |
| 432. All O`one Data Structure | Design Hash Table Linked List Doubly-Linked List | Hard | |
| 433. Minimum Genetic Mutation | Breadth-First Search Hash Table String | Medium | |
| 434. Number of Segments in a String | String | Easy | |
| 435. Non-overlapping Intervals | Greedy Array Dynamic Programming Sorting | Medium | |
| 436. Find Right Interval | Array Binary Search Sorting | Medium | |
| 437. Path Sum III | Tree Depth-First Search Binary Tree | Medium | |
| 438. Find All Anagrams in a String | Hash Table String Sliding Window | Medium | |
| 439. Ternary Expression Parser | Stack Recursion String | Medium | |
| 440. K-th Smallest in Lexicographical Order | Trie | Hard | |
| 441. Arranging Coins | Math Binary Search | Easy | |
| 442. Find All Duplicates in an Array | Array Hash Table | Medium | |
| 443. String Compression | Two Pointers String | Medium | |
| 444. Sequence Reconstruction | Graph Topological Sort Array | Medium | |
| 445. Add Two Numbers II | Stack Linked List Math | Medium | |
| 446. Arithmetic Slices II - Subsequence | Array Dynamic Programming | Hard | |
| 447. Number of Boomerangs | Array Hash Table Math | Medium | |
| 448. Find All Numbers Disappeared in an Array | Array Hash Table | Easy | |
| 449. Serialize and Deserialize BST | Tree Depth-First Search Breadth-First Search Design Binary Search Tree String Binary Tree | Medium | |
| 450. Delete Node in a BST | Tree Binary Search Tree Binary Tree | Medium | |
| 451. Sort Characters By Frequency | Hash Table String Bucket Sort Counting Sorting Heap (Priority Queue) | Medium | |
| 452. Minimum Number of Arrows to Burst Balloons | Greedy Array Sorting | Medium | |
| 453. Minimum Moves to Equal Array Elements | Array Math | Medium | |
| 454. 4Sum II | Array Hash Table | Medium | |
| 455. Assign Cookies | Greedy Array Two Pointers Sorting | Easy | |
| 456. 132 Pattern | Stack Array Binary Search Ordered Set Monotonic Stack | Medium | |
| 457. Circular Array Loop | Array Hash Table Two Pointers | Medium | |
| 458. Poor Pigs | Math Dynamic Programming Combinatorics | Hard | |
| 459. Repeated Substring Pattern | String String Matching | Easy | |
| 460. LFU Cache | Design Hash Table Linked List Doubly-Linked List | Hard | |
| 461. Hamming Distance | Bit Manipulation | Easy | |
| 462. Minimum Moves to Equal Array Elements II | Array Math Sorting | Medium | |
| 463. Island Perimeter | Depth-First Search Breadth-First Search Array Matrix | Easy | |
| 464. Can I Win | Bit Manipulation Memoization Math Dynamic Programming Bitmask Game Theory | Medium | |
| 465. Optimal Account Balancing | Bit Manipulation Array Dynamic Programming Backtracking Bitmask | Hard | |
| 466. Count The Repetitions | String Dynamic Programming | Hard | |
| 467. Unique Substrings in Wraparound String | String Dynamic Programming | Medium | |
| 468. Validate IP Address | String | Medium | |
| 469. Convex Polygon | Geometry Array Math | Medium | |
| 470. Implement Rand10() Using Rand7() | Math Rejection Sampling Probability and Statistics Randomized | Medium | |
| 471. Encode String with Shortest Length | String Dynamic Programming | Hard | |
| 472. Concatenated Words | Depth-First Search Trie Array String Dynamic Programming Sorting | Hard | |
| 473. Matchsticks to Square | Bit Manipulation Array Dynamic Programming Backtracking Bitmask | Medium | |
| 474. Ones and Zeroes | Array String Dynamic Programming | Medium | |
| 475. Heaters | Array Two Pointers Binary Search Sorting | Medium | |
| 476. Number Complement | Bit Manipulation | Easy | |
| 477. Total Hamming Distance | Bit Manipulation Array Math | Medium | |
| 478. Generate Random Point in a Circle | Geometry Math Rejection Sampling Randomized | Medium | |
| 479. Largest Palindrome Product | Math Enumeration | Hard | |
| 480. Sliding Window Median | Array Hash Table Sliding Window Heap (Priority Queue) | Hard | |
| 481. Magical String | Two Pointers String | Medium | |
| 482. License Key Formatting | String | Easy | |
| 483. Smallest Good Base | Math Binary Search | Hard | |
| 484. Find Permutation | Stack Greedy Array String | Medium | |
| 485. Max Consecutive Ones | Array | Easy | |
| 486. Predict the Winner | Recursion Array Math Dynamic Programming Game Theory | Medium | |
| 487. Max Consecutive Ones II | Array Dynamic Programming Sliding Window | Medium | |
| 488. Zuma Game | Stack Breadth-First Search Memoization String Dynamic Programming | Hard | |
| 489. Robot Room Cleaner | Backtracking Interactive | Hard | |
| 490. The Maze | Depth-First Search Breadth-First Search Array Matrix | Medium | |
| 491. Non-decreasing Subsequences | Bit Manipulation Array Hash Table Backtracking | Medium | |
| 492. Construct the Rectangle | Math | Easy | |
| 493. Reverse Pairs | Binary Indexed Tree Segment Tree Array Binary Search Divide and Conquer Ordered Set Merge Sort | Hard | |
| 494. Target Sum | Array Dynamic Programming Backtracking | Medium | |
| 495. Teemo Attacking | Array Simulation | Easy | |
| 496. Next Greater Element I | Stack Array Hash Table Monotonic Stack | Easy | |
| 497. Random Point in Non-overlapping Rectangles | Reservoir Sampling Array Math Binary Search Ordered Set Prefix Sum Randomized | Medium | |
| 498. Diagonal Traverse | Array Matrix Simulation | Medium | |
| 499. The Maze III | Depth-First Search Breadth-First Search Graph Array String Matrix Shortest Path Heap (Priority Queue) | Hard | |
| 500. Keyboard Row | Array Hash Table String | Easy | |
| 501. Find Mode in Binary Search Tree | Tree Depth-First Search Binary Search Tree Binary Tree | Easy | |
| 502. IPO | Greedy Array Sorting Heap (Priority Queue) | Hard | |
| 503. Next Greater Element II | Stack Array Monotonic Stack | Medium | |
| 504. Base 7 | Math String | Easy | |
| 505. The Maze II | Depth-First Search Breadth-First Search Graph Array Matrix Shortest Path Heap (Priority Queue) | Medium | |
| 506. Relative Ranks | Array Sorting Heap (Priority Queue) | Easy | |
| 507. Perfect Number | Math | Easy | |
| 508. Most Frequent Subtree Sum | Tree Depth-First Search Hash Table Binary Tree | Medium | |
| 509. Fibonacci Number | Recursion Memoization Math Dynamic Programming | Easy | |
| 510. Inorder Successor in BST II | Tree Binary Search Tree Binary Tree | Medium | |
| 513. Find Bottom Left Tree Value | Tree Depth-First Search Breadth-First Search Binary Tree | Medium | |
| 514. Freedom Trail | Depth-First Search Breadth-First Search String Dynamic Programming | Hard | |
| 515. Find Largest Value in Each Tree Row | Tree Depth-First Search Breadth-First Search Binary Tree | Medium | |
| 516. Longest Palindromic Subsequence | String Dynamic Programming | Medium | |
| 517. Super Washing Machines | Greedy Array | Hard | |
| 518. Coin Change II | Array Dynamic Programming | Medium | |
| 519. Random Flip Matrix | Reservoir Sampling Hash Table Math Randomized | Medium | |
| 520. Detect Capital | String | Easy | |
| 521. Longest Uncommon Subsequence I | String | Easy | |
| 522. Longest Uncommon Subsequence II | Array Hash Table Two Pointers String Sorting | Medium | |
| 523. Continuous Subarray Sum | Array Hash Table Math Prefix Sum | Medium | |
| 524. Longest Word in Dictionary through Deleting | Array Two Pointers String Sorting | Medium | |
| 525. Contiguous Array | Array Hash Table Prefix Sum | Medium | |
| 526. Beautiful Arrangement | Bit Manipulation Array Dynamic Programming Backtracking Bitmask | Medium | |
| 527. Word Abbreviation | Greedy Trie Array String Sorting | Hard | |
| 528. Random Pick with Weight | Array Math Binary Search Prefix Sum Randomized | Medium | |
| 529. Minesweeper | Depth-First Search Breadth-First Search Array Matrix | Medium | |
| 530. Minimum Absolute Difference in BST | Tree Depth-First Search Breadth-First Search Binary Search Tree Binary Tree | Easy | |
| 531. Lonely Pixel I | Array Hash Table Matrix | Medium | |
| 532. K-diff Pairs in an Array | Array Hash Table Two Pointers Binary Search Sorting | Medium | |
| 533. Lonely Pixel II | Array Hash Table Matrix | Medium | |
| 535. Encode and Decode TinyURL | Design Hash Table String Hash Function | Medium | |
| 536. Construct Binary Tree from String | Stack Tree Depth-First Search String Binary Tree | Medium | |
| 537. Complex Number Multiplication | Math String Simulation | Medium | |
| 538. Convert BST to Greater Tree | Tree Depth-First Search Binary Search Tree Binary Tree | Medium | |
| 539. Minimum Time Difference | Array Math String Sorting | Medium | |
| 540. Single Element in a Sorted Array | Array Binary Search | Medium | |
| 541. Reverse String II | Two Pointers String | Easy | |
| 542. 01 Matrix | Breadth-First Search Array Dynamic Programming Matrix | Medium | |
| 543. Diameter of Binary Tree | Tree Depth-First Search Binary Tree | Easy | |
| 544. Output Contest Matches | Recursion String Simulation | Medium | |
| 545. Boundary of Binary Tree | Tree Depth-First Search Binary Tree | Medium | |
| 546. Remove Boxes | Memoization Array Dynamic Programming | Hard | |
| 547. Number of Provinces | Depth-First Search Breadth-First Search Union Find Graph | Medium | |
| 548. Split Array with Equal Sum | Array Hash Table Prefix Sum | Hard | |
| 549. Binary Tree Longest Consecutive Sequence II | Tree Depth-First Search Binary Tree | Medium | |
| 551. Student Attendance Record I | String | Easy | |
| 552. Student Attendance Record II | Dynamic Programming | Hard | |
| 553. Optimal Division | Array Math Dynamic Programming | Medium | |
| 554. Brick Wall | Array Hash Table | Medium | |
| 555. Split Concatenated Strings | Greedy Array String | Medium | |
| 556. Next Greater Element III | Math Two Pointers String | Medium | |
| 557. Reverse Words in a String III | Two Pointers String | Easy | |
| 558. Logical OR of Two Binary Grids Represented as Quad-Trees | Tree Divide and Conquer | Medium | |
| 559. Maximum Depth of N-ary Tree | Tree Depth-First Search Breadth-First Search | Easy | |
| 560. Subarray Sum Equals K | Array Hash Table Prefix Sum | Medium | |
| 561. Array Partition | Greedy Array Counting Sort Sorting | Easy | |
| 562. Longest Line of Consecutive One in Matrix | Array Dynamic Programming Matrix | Medium | |
| 563. Binary Tree Tilt | Tree Depth-First Search Binary Tree | Easy | |
| 564. Find the Closest Palindrome | Math String | Hard | |
| 565. Array Nesting | Depth-First Search Array | Medium | |
| 566. Reshape the Matrix | Array Matrix Simulation | Easy | |
| 567. Permutation in String | Hash Table Two Pointers String Sliding Window | Medium | |
| 568. Maximum Vacation Days | Array Dynamic Programming Matrix | Hard | |
| 572. Subtree of Another Tree | Tree Depth-First Search Binary Tree String Matching Hash Function | Easy | |
| 573. Squirrel Simulation | Array Math | Medium | |
| 575. Distribute Candies | Array Hash Table | Easy | |
| 576. Out of Boundary Paths | Dynamic Programming | Medium | |
| 581. Shortest Unsorted Continuous Subarray | Stack Greedy Array Two Pointers Sorting Monotonic Stack | Medium | |
| 582. Kill Process | Tree Depth-First Search Breadth-First Search Array Hash Table | Medium | |
| 583. Delete Operation for Two Strings | String Dynamic Programming | Medium | |
| 587. Erect the Fence | Geometry Array Math | Hard | |
| 588. Design In-Memory File System | Design Trie Hash Table String Sorting | Hard | |
| 589. N-ary Tree Preorder Traversal | Stack Tree Depth-First Search | Easy | |
| 590. N-ary Tree Postorder Traversal | Stack Tree Depth-First Search | Easy | |
| 591. Tag Validator | Stack String | Hard | |
| 592. Fraction Addition and Subtraction | Math String Simulation | Medium | |
| 593. Valid Square | Geometry Math | Medium | |
| 594. Longest Harmonious Subsequence | Array Hash Table Counting Sorting Sliding Window | Easy | |
| 598. Range Addition II | Array Math | Easy | |
| 599. Minimum Index Sum of Two Lists | Array Hash Table String | Easy | |
| 600. Non-negative Integers without Consecutive Ones | Dynamic Programming | Hard | |
| 604. Design Compressed String Iterator | Design Array String Iterator | Easy | |
| 605. Can Place Flowers | Greedy Array | Easy | |
| 606. Construct String from Binary Tree | Tree Depth-First Search String Binary Tree | Medium | |
| 609. Find Duplicate File in System | Array Hash Table String | Medium | |
| 611. Valid Triangle Number | Greedy Array Two Pointers Binary Search Sorting | Medium | |
| 616. Add Bold Tag in String | Trie Array Hash Table String String Matching | Medium | |
| 617. Merge Two Binary Trees | Tree Depth-First Search Breadth-First Search Binary Tree | Easy | |
| 621. Task Scheduler | Greedy Array Hash Table Counting Sorting Heap (Priority Queue) | Medium | |
| 622. Design Circular Queue | Design Queue Array Linked List | Medium | |
| 623. Add One Row to Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Medium | |
| 624. Maximum Distance in Arrays | Greedy Array | Medium | |
| 625. Minimum Factorization | Greedy Math | Medium | |
| 628. Maximum Product of Three Numbers | Array Math Sorting | Easy | |
| 629. K Inverse Pairs Array | Dynamic Programming | Hard | |
| 630. Course Schedule III | Greedy Array Sorting Heap (Priority Queue) | Hard | |
| 631. Design Excel Sum Formula | Graph Design Topological Sort Array Hash Table String Matrix | Hard | |
| 632. Smallest Range Covering Elements from K Lists | Greedy Array Hash Table Sorting Sliding Window Heap (Priority Queue) | Hard | |
| 633. Sum of Square Numbers | Math Two Pointers Binary Search | Medium | |
| 634. Find the Derangement of An Array | Math Dynamic Programming Combinatorics | Medium | |
| 635. Design Log Storage System | Design Hash Table String Ordered Set | Medium | |
| 636. Exclusive Time of Functions | Stack Array | Medium | |
| 637. Average of Levels in Binary Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Easy | |
| 638. Shopping Offers | Bit Manipulation Memoization Array Dynamic Programming Backtracking Bitmask | Medium | |
| 639. Decode Ways II | String Dynamic Programming | Hard | |
| 640. Solve the Equation | Math String Simulation | Medium | |
| 641. Design Circular Deque | Design Queue Array Linked List | Medium | |
| 642. Design Search Autocomplete System | Depth-First Search Design Trie String Data Stream Sorting Heap (Priority Queue) | Hard | |
| 643. Maximum Average Subarray I | Array Sliding Window | Easy | |
| 644. Maximum Average Subarray II | Array Binary Search Prefix Sum | Hard | |
| 645. Set Mismatch | Bit Manipulation Array Hash Table Sorting | Easy | |
| 646. Maximum Length of Pair Chain | Greedy Array Dynamic Programming Sorting | Medium | |
| 647. Palindromic Substrings | Two Pointers String Dynamic Programming | Medium | |
| 648. Replace Words | Trie Array Hash Table String | Medium | |
| 649. Dota2 Senate | Greedy Queue String | Medium | |
| 650. 2 Keys Keyboard | Math Dynamic Programming | Medium | |
| 651. 4 Keys Keyboard | Math Dynamic Programming | Medium | |
| 652. Find Duplicate Subtrees | Tree Depth-First Search Hash Table Binary Tree | Medium | |
| 653. Two Sum IV - Input is a BST | Tree Depth-First Search Breadth-First Search Binary Search Tree Hash Table Two Pointers Binary Tree | Easy | |
| 654. Maximum Binary Tree | Stack Tree Array Divide and Conquer Binary Tree Monotonic Stack | Medium | |
| 655. Print Binary Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Medium | |
| 656. Coin Path | Array Dynamic Programming | Hard | |
| 657. Robot Return to Origin | String Simulation | Easy | |
| 658. Find K Closest Elements | Array Two Pointers Binary Search Sorting Sliding Window Heap (Priority Queue) | Medium | |
| 659. Split Array into Consecutive Subsequences | Greedy Array Hash Table Heap (Priority Queue) | Medium | |
| 660. Remove 9 | Math | Hard | |
| 661. Image Smoother | Array Matrix | Easy | |
| 662. Maximum Width of Binary Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Medium | |
| 663. Equal Tree Partition | Tree Depth-First Search Binary Tree | Medium | |
| 664. Strange Printer | String Dynamic Programming | Hard | |
| 665. Non-decreasing Array | Array | Medium | |
| 666. Path Sum IV | Tree Depth-First Search Array Hash Table Binary Tree | Medium | |
| 667. Beautiful Arrangement II | Array Math | Medium | |
| 668. Kth Smallest Number in Multiplication Table | Math Binary Search | Hard | |
| 669. Trim a Binary Search Tree | Tree Depth-First Search Binary Search Tree Binary Tree | Medium | |
| 670. Maximum Swap | Greedy Math | Medium | |
| 671. Second Minimum Node In a Binary Tree | Tree Depth-First Search Binary Tree | Easy | |
| 672. Bulb Switcher II | Bit Manipulation Depth-First Search Breadth-First Search Math | Medium | |
| 673. Number of Longest Increasing Subsequence | Binary Indexed Tree Segment Tree Array Dynamic Programming | Medium | |
| 674. Longest Continuous Increasing Subsequence | Array | Easy | |
| 675. Cut Off Trees for Golf Event | Breadth-First Search Array Matrix Heap (Priority Queue) | Hard | |
| 676. Implement Magic Dictionary | Depth-First Search Design Trie Hash Table String | Medium | |
| 677. Map Sum Pairs | Design Trie Hash Table String | Medium | |
| 678. Valid Parenthesis String | Stack Greedy String Dynamic Programming | Medium | |
| 679. 24 Game | Array Math Backtracking | Hard | |
| 680. Valid Palindrome II | Greedy Two Pointers String | Easy | |
| 681. Next Closest Time | Hash Table String Backtracking Enumeration | Medium | |
| 682. Baseball Game | Stack Array Simulation | Easy | |
| 683. K Empty Slots | Binary Indexed Tree Segment Tree Queue Array Ordered Set Sliding Window Monotonic Queue Heap (Priority Queue) | Hard | |
| 684. Redundant Connection | Depth-First Search Breadth-First Search Union Find Graph | Medium | |
| 685. Redundant Connection II | Depth-First Search Breadth-First Search Union Find Graph | Hard | |
| 686. Repeated String Match | String String Matching | Medium | |
| 687. Longest Univalue Path | Tree Depth-First Search Binary Tree | Medium | |
| 688. Knight Probability in Chessboard | Dynamic Programming | Medium | |
| 689. Maximum Sum of 3 Non-Overlapping Subarrays | Array Dynamic Programming Prefix Sum Sliding Window | Hard | |
| 690. Employee Importance | Tree Depth-First Search Breadth-First Search Array Hash Table | Medium | |
| 691. Stickers to Spell Word | Bit Manipulation Memoization Array Hash Table String Dynamic Programming Backtracking Bitmask | Hard | |
| 692. Top K Frequent Words | Trie Array Hash Table String Bucket Sort Counting Sorting Heap (Priority Queue) | Medium | |
| 693. Binary Number with Alternating Bits | Bit Manipulation | Easy | |
| 694. Number of Distinct Islands | Depth-First Search Breadth-First Search Union Find Hash Table Hash Function | Medium | |
| 695. Max Area of Island | Depth-First Search Breadth-First Search Union Find Array Matrix | Medium | |
| 696. Count Binary Substrings | Two Pointers String | Easy | |
| 697. Degree of an Array | Array Hash Table | Easy | |
| 698. Partition to K Equal Sum Subsets | Bit Manipulation Memoization Array Dynamic Programming Backtracking Bitmask | Medium | |
| 699. Falling Squares | Segment Tree Array Ordered Set | Hard | |
| 700. Search in a Binary Search Tree | Tree Binary Search Tree Binary Tree | Easy | |
| 701. Insert into a Binary Search Tree | Tree Binary Search Tree Binary Tree | Medium | |
| 702. Search in a Sorted Array of Unknown Size | Array Binary Search Interactive | Medium | |
| 703. Kth Largest Element in a Stream | Tree Design Binary Search Tree Binary Tree Data Stream Heap (Priority Queue) | Easy | |
| 704. Binary Search | Array Binary Search | Easy | |
| 705. Design HashSet | Design Array Hash Table Linked List Hash Function | Easy | |
| 706. Design HashMap | Design Array Hash Table Linked List Hash Function | Easy | |
| 707. Design Linked List | Design Linked List | Medium | |
| 708. Insert into a Sorted Circular Linked List | Linked List | Medium | |
| 709. To Lower Case | String | Easy | |
| 710. Random Pick with Blacklist | Array Hash Table Math Binary Search Sorting Randomized | Hard | |
| 711. Number of Distinct Islands II | Depth-First Search Breadth-First Search Union Find Hash Table Hash Function | Hard | |
| 712. Minimum ASCII Delete Sum for Two Strings | String Dynamic Programming | Medium | |
| 713. Subarray Product Less Than K | Array Sliding Window | Medium | |
| 714. Best Time to Buy and Sell Stock with Transaction Fee | Greedy Array Dynamic Programming | Medium | |
| 715. Range Module | Design Segment Tree Ordered Set | Hard | |
| 716. Max Stack | Stack Design Linked List Doubly-Linked List Ordered Set | Hard | |
| 717. 1-bit and 2-bit Characters | Array | Easy | |
| 718. Maximum Length of Repeated Subarray | Array Binary Search Dynamic Programming Sliding Window Hash Function Rolling Hash | Medium | |
| 719. Find K-th Smallest Pair Distance | Array Two Pointers Binary Search Sorting | Hard | |
| 720. Longest Word in Dictionary | Trie Array Hash Table String Sorting | Medium | |
| 721. Accounts Merge | Depth-First Search Breadth-First Search Union Find Array Hash Table String Sorting | Medium | |
| 722. Remove Comments | Array String | Medium | |
| 723. Candy Crush | Array Two Pointers Matrix Simulation | Medium | |
| 724. Find Pivot Index | Array Prefix Sum | Easy | |
| 725. Split Linked List in Parts | Linked List | Medium | |
| 726. Number of Atoms | Stack Hash Table String Sorting | Hard | |
| 727. Minimum Window Subsequence | String Dynamic Programming Sliding Window | Hard | |
| 728. Self Dividing Numbers | Math | Easy | |
| 729. My Calendar I | Design Segment Tree Array Binary Search Ordered Set | Medium | |
| 730. Count Different Palindromic Subsequences | String Dynamic Programming | Hard | |
| 731. My Calendar II | Design Segment Tree Array Binary Search Ordered Set Prefix Sum | Medium | |
| 732. My Calendar III | Design Segment Tree Binary Search Ordered Set Prefix Sum | Hard | |
| 733. Flood Fill | Depth-First Search Breadth-First Search Array Matrix | Easy | |
| 734. Sentence Similarity | Array Hash Table String | Easy | |
| 735. Asteroid Collision | Stack Array Simulation | Medium | |
| 736. Parse Lisp Expression | Stack Recursion Hash Table String | Hard | |
| 737. Sentence Similarity II | Depth-First Search Breadth-First Search Union Find Array Hash Table String | Medium | |
| 738. Monotone Increasing Digits | Greedy Math | Medium | |
| 739. Daily Temperatures | Stack Array Monotonic Stack | Medium | |
| 740. Delete and Earn | Array Hash Table Dynamic Programming | Medium | |
| 741. Cherry Pickup | Array Dynamic Programming Matrix | Hard | |
| 742. Closest Leaf in a Binary Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Medium | |
| 743. Network Delay Time | Depth-First Search Breadth-First Search Graph Shortest Path Heap (Priority Queue) | Medium | |
| 744. Find Smallest Letter Greater Than Target | Array Binary Search | Easy | |
| 745. Prefix and Suffix Search | Design Trie Array Hash Table String | Hard | |
| 746. Min Cost Climbing Stairs | Array Dynamic Programming | Easy | |
| 747. Largest Number At Least Twice of Others | Array Sorting | Easy | |
| 748. Shortest Completing Word | Array Hash Table String | Easy | |
| 749. Contain Virus | Depth-First Search Breadth-First Search Array Matrix Simulation | Hard | |
| 750. Number Of Corner Rectangles | Array Math Dynamic Programming Matrix | Medium | |
| 751. IP to CIDR | Bit Manipulation String | Medium | |
| 752. Open the Lock | Breadth-First Search Array Hash Table String | Medium | |
| 753. Cracking the Safe | Depth-First Search Graph Eulerian Circuit | Hard | |
| 754. Reach a Number | Math Binary Search | Medium | |
| 755. Pour Water | Array Simulation | Medium | |
| 756. Pyramid Transition Matrix | Bit Manipulation Depth-First Search Breadth-First Search | Medium | |
| 757. Set Intersection Size At Least Two | Greedy Array Sorting | Hard | |
| 758. Bold Words in String | Trie Array Hash Table String String Matching | Medium | |
| 759. Employee Free Time | Array Sorting Line Sweep Heap (Priority Queue) | Hard | |
| 760. Find Anagram Mappings | Array Hash Table | Easy | |
| 761. Special Binary String | Recursion String | Hard | |
| 762. Prime Number of Set Bits in Binary Representation | Bit Manipulation Math | Easy | |
| 763. Partition Labels | Greedy Hash Table Two Pointers String | Medium | |
| 764. Largest Plus Sign | Array Dynamic Programming | Medium | |
| 765. Couples Holding Hands | Greedy Depth-First Search Breadth-First Search Union Find Graph | Hard | |
| 766. Toeplitz Matrix | Array Matrix | Easy | |
| 767. Reorganize String | Greedy Hash Table String Counting Sorting Heap (Priority Queue) | Medium | |
| 768. Max Chunks To Make Sorted II | Stack Greedy Array Sorting Monotonic Stack | Hard | |
| 769. Max Chunks To Make Sorted | Stack Greedy Array Sorting Monotonic Stack | Medium | |
| 770. Basic Calculator IV | Stack Recursion Hash Table Math String | Hard | |
| 771. Jewels and Stones | Hash Table String | Easy | |
| 772. Basic Calculator III | Stack Recursion Math String | Hard | |
| 773. Sliding Puzzle | Breadth-First Search Memoization Array Dynamic Programming Backtracking Matrix | Hard | |
| 774. Minimize Max Distance to Gas Station | Array Binary Search | Hard | |
| 775. Global and Local Inversions | Array Math | Medium | |
| 776. Split BST | Tree Binary Search Tree Recursion Binary Tree | Medium | |
| 777. Swap Adjacent in LR String | Two Pointers String | Medium | |
| 778. Swim in Rising Water | Depth-First Search Breadth-First Search Union Find Array Binary Search Matrix Heap (Priority Queue) | Hard | |
| 779. K-th Symbol in Grammar | Bit Manipulation Recursion Math | Medium | |
| 780. Reaching Points | Math | Hard | |
| 781. Rabbits in Forest | Greedy Array Hash Table Math | Medium | |
| 782. Transform to Chessboard | Bit Manipulation Array Math Matrix | Hard | |
| 783. Minimum Distance Between BST Nodes | Tree Depth-First Search Breadth-First Search Binary Search Tree Binary Tree | Easy | |
| 784. Letter Case Permutation | Bit Manipulation String Backtracking | Medium | |
| 785. Is Graph Bipartite | Depth-First Search Breadth-First Search Union Find Graph | Medium | |
| 786. K-th Smallest Prime Fraction | Array Two Pointers Binary Search Sorting Heap (Priority Queue) | Medium | |
| 787. Cheapest Flights Within K Stops | Depth-First Search Breadth-First Search Graph Dynamic Programming Shortest Path Heap (Priority Queue) | Medium | |
| 788. Rotated Digits | Math Dynamic Programming | Medium | |
| 789. Escape The Ghosts | Array Math | Medium | |
| 790. Domino and Tromino Tiling | Dynamic Programming | Medium | |
| 791. Custom Sort String | Hash Table String Sorting | Medium | |
| 792. Number of Matching Subsequences | Trie Array Hash Table String Binary Search Dynamic Programming Sorting | Medium | |
| 793. Preimage Size of Factorial Zeroes Function | Math Binary Search | Hard | |
| 794. Valid Tic-Tac-Toe State | Array Matrix | Medium | |
| 795. Number of Subarrays with Bounded Maximum | Array Two Pointers | Medium | |
| 796. Rotate String | String String Matching | Easy | |
| 797. All Paths From Source to Target | Depth-First Search Breadth-First Search Graph Backtracking | Medium | |
| 798. Smallest Rotation with Highest Score | Array Prefix Sum | Hard | |
| 799. Champagne Tower | Dynamic Programming | Medium | |
| 800. Similar RGB Color | Math String Enumeration | Easy | |
| 801. Minimum Swaps To Make Sequences Increasing | Array Dynamic Programming | Hard | |
| 802. Find Eventual Safe States | Depth-First Search Breadth-First Search Graph Topological Sort | Medium | |
| 803. Bricks Falling When Hit | Union Find Array Matrix | Hard | |
| 804. Unique Morse Code Words | Array Hash Table String | Easy | |
| 805. Split Array With Same Average | Bit Manipulation Array Math Dynamic Programming Bitmask | Hard | |
| 806. Number of Lines To Write String | Array String | Easy | |
| 807. Max Increase to Keep City Skyline | Greedy Array Matrix | Medium | |
| 808. Soup Servings | Math Dynamic Programming Probability and Statistics | Medium | |
| 809. Expressive Words | Array Two Pointers String | Medium | |
| 810. Chalkboard XOR Game | Bit Manipulation Brainteaser Array Math Game Theory | Hard | |
| 811. Subdomain Visit Count | Array Hash Table String Counting | Medium | |
| 812. Largest Triangle Area | Geometry Array Math | Easy | |
| 813. Largest Sum of Averages | Array Dynamic Programming Prefix Sum | Medium | |
| 814. Binary Tree Pruning | Tree Depth-First Search Binary Tree | Medium | |
| 815. Bus Routes | Breadth-First Search Array Hash Table | Hard | |
| 816. Ambiguous Coordinates | String Backtracking Enumeration | Medium | |
| 817. Linked List Components | Array Hash Table Linked List | Medium | |
| 818. Race Car | Dynamic Programming | Hard | |
| 819. Most Common Word | Array Hash Table String Counting | Easy | |
| 820. Short Encoding of Words | Trie Array Hash Table String | Medium | |
| 821. Shortest Distance to a Character | Array Two Pointers String | Easy | |
| 822. Card Flipping Game | Array Hash Table | Medium | |
| 823. Binary Trees With Factors | Array Hash Table Dynamic Programming Sorting | Medium | |
| 824. Goat Latin | String | Easy | |
| 825. Friends Of Appropriate Ages | Array Two Pointers Binary Search Sorting | Medium | |
| 826. Most Profit Assigning Work | Greedy Array Two Pointers Binary Search Sorting | Medium | |
| 827. Making A Large Island | Depth-First Search Breadth-First Search Union Find Array Matrix | Hard | |
| 828. Count Unique Characters of All Substrings of a Given String | Hash Table String Dynamic Programming | Hard | |
| 829. Consecutive Numbers Sum | Math Enumeration | Hard | |
| 830. Positions of Large Groups | String | Easy | |
| 831. Masking Personal Information | String | Medium | |
| 832. Flipping an Image | Bit Manipulation Array Two Pointers Matrix Simulation | Easy | |
| 833. Find And Replace in String | Array Hash Table String Sorting | Medium | |
| 834. Sum of Distances in Tree | Tree Depth-First Search Graph Dynamic Programming | Hard | |
| 835. Image Overlap | Array Matrix | Medium | |
| 836. Rectangle Overlap | Geometry Math | Easy | |
| 837. New 21 Game | Math Dynamic Programming Sliding Window Probability and Statistics | Medium | |
| 838. Push Dominoes | Two Pointers String Dynamic Programming | Medium | |
| 839. Similar String Groups | Depth-First Search Breadth-First Search Union Find Array Hash Table String | Hard | |
| 840. Magic Squares In Grid | Array Hash Table Math Matrix | Medium | |
| 841. Keys and Rooms | Depth-First Search Breadth-First Search Graph | Medium | |
| 842. Split Array into Fibonacci Sequence | String Backtracking | Medium | |
| 843. Guess the Word | Array Math String Game Theory Interactive | Hard | |
| 844. Backspace String Compare | Stack Two Pointers String Simulation | Easy | |
| 845. Longest Mountain in Array | Array Two Pointers Dynamic Programming Enumeration | Medium | |
| 846. Hand of Straights | Greedy Array Hash Table Sorting | Medium | |
| 847. Shortest Path Visiting All Nodes | Bit Manipulation Breadth-First Search Graph Dynamic Programming Bitmask | Hard | |
| 848. Shifting Letters | Array String Prefix Sum | Medium | |
| 849. Maximize Distance to Closest Person | Array | Medium | |
| 850. Rectangle Area II | Segment Tree Array Ordered Set Line Sweep | Hard | |
| 851. Loud and Rich | Depth-First Search Graph Topological Sort Array | Medium | |
| 852. Peak Index in a Mountain Array | Array Binary Search | Medium | |
| 853. Car Fleet | Stack Array Sorting Monotonic Stack | Medium | |
| 854. K-Similar Strings | Breadth-First Search Hash Table String | Hard | |
| 855. Exam Room | Design Ordered Set Heap (Priority Queue) | Medium | |
| 856. Score of Parentheses | Stack String | Medium | |
| 857. Minimum Cost to Hire K Workers | Greedy Array Sorting Heap (Priority Queue) | Hard | |
| 858. Mirror Reflection | Geometry Math Number Theory | Medium | |
| 859. Buddy Strings | Hash Table String | Easy | |
| 860. Lemonade Change | Greedy Array | Easy | |
| 861. Score After Flipping Matrix | Greedy Bit Manipulation Array Matrix | Medium | |
| 862. Shortest Subarray with Sum at Least K | Queue Array Binary Search Prefix Sum Sliding Window Monotonic Queue Heap (Priority Queue) | Hard | |
| 863. All Nodes Distance K in Binary Tree | Tree Depth-First Search Breadth-First Search Hash Table Binary Tree | Medium | |
| 864. Shortest Path to Get All Keys | Bit Manipulation Breadth-First Search Array Matrix | Hard | |
| 865. Smallest Subtree with all the Deepest Nodes | Tree Depth-First Search Breadth-First Search Hash Table Binary Tree | Medium | |
| 866. Prime Palindrome | Math | Medium | |
| 867. Transpose Matrix | Array Matrix Simulation | Easy | |
| 868. Binary Gap | Bit Manipulation | Easy | |
| 869. Reordered Power of 2 | Hash Table Math Counting Enumeration Sorting | Medium | |
| 870. Advantage Shuffle | Greedy Array Two Pointers Sorting | Medium | |
| 871. Minimum Number of Refueling Stops | Greedy Array Dynamic Programming Heap (Priority Queue) | Hard | |
| 872. Leaf-Similar Trees | Tree Depth-First Search Binary Tree | Easy | |
| 873. Length of Longest Fibonacci Subsequence | Array Hash Table Dynamic Programming | Medium | |
| 874. Walking Robot Simulation | Array Hash Table Simulation | Medium | |
| 875. Koko Eating Bananas | Array Binary Search | Medium | |
| 876. Middle of the Linked List | Linked List Two Pointers | Easy | |
| 877. Stone Game | Array Math Dynamic Programming Game Theory | Medium | |
| 878. Nth Magical Number | Math Binary Search | Hard | |
| 879. Profitable Schemes | Array Dynamic Programming | Hard | |
| 880. Decoded String at Index | Stack String | Medium | |
| 881. Boats to Save People | Greedy Array Two Pointers Sorting | Medium | |
| 882. Reachable Nodes In Subdivided Graph | Graph Shortest Path Heap (Priority Queue) | Hard | |
| 883. Projection Area of 3D Shapes | Geometry Array Math Matrix | Easy | |
| 884. Uncommon Words from Two Sentences | Hash Table String Counting | Easy | |
| 885. Spiral Matrix III | Array Matrix Simulation | Medium | |
| 886. Possible Bipartition | Depth-First Search Breadth-First Search Union Find Graph | Medium | |
| 887. Super Egg Drop | Math Binary Search Dynamic Programming | Hard | |
| 888. Fair Candy Swap | Array Hash Table Binary Search Sorting | Easy | |
| 889. Construct Binary Tree from Preorder and Postorder Traversal | Tree Array Hash Table Divide and Conquer Binary Tree | Medium | |
| 890. Find and Replace Pattern | Array Hash Table String | Medium | |
| 891. Sum of Subsequence Widths | Array Math Sorting | Hard | |
| 892. Surface Area of 3D Shapes | Geometry Array Math Matrix | Easy | |
| 893. Groups of Special-Equivalent Strings | Array Hash Table String Sorting | Medium | |
| 894. All Possible Full Binary Trees | Tree Recursion Memoization Dynamic Programming Binary Tree | Medium | |
| 895. Maximum Frequency Stack | Stack Design Hash Table Ordered Set | Hard | |
| 896. Monotonic Array | Array | Easy | |
| 897. Increasing Order Search Tree | Stack Tree Depth-First Search Binary Search Tree Binary Tree | Easy | |
| 898. Bitwise ORs of Subarrays | Bit Manipulation Array Dynamic Programming | Medium | |
| 899. Orderly Queue | Math String Sorting | Hard | |
| 900. RLE Iterator | Design Array Counting Iterator | Medium | |
| 901. Online Stock Span | Stack Design Data Stream Monotonic Stack | Medium | |
| 902. Numbers At Most N Given Digit Set | Array Math String Binary Search Dynamic Programming | Hard | |
| 903. Valid Permutations for DI Sequence | String Dynamic Programming Prefix Sum | Hard | |
| 904. Fruit Into Baskets | Array Hash Table Sliding Window | Medium | |
| 905. Sort Array By Parity | Array Two Pointers Sorting | Easy | |
| 906. Super Palindromes | Math String Enumeration | Hard | |
| 907. Sum of Subarray Minimums | Stack Array Dynamic Programming Monotonic Stack | Medium | |
| 908. Smallest Range I | Array Math | Easy | |
| 909. Snakes and Ladders | Breadth-First Search Array Matrix | Medium | |
| 910. Smallest Range II | Greedy Array Math Sorting | Medium | |
| 911. Online Election | Design Array Hash Table Binary Search | Medium | |
| 912. Sort an Array | Array Divide and Conquer Bucket Sort Counting Sort Radix Sort Sorting Heap (Priority Queue) Merge Sort | Medium | |
| 913. Cat and Mouse | Graph Topological Sort Memoization Math Dynamic Programming Game Theory | Hard | |
| 914. X of a Kind in a Deck of Cards | Array Hash Table Math Counting Number Theory | Easy | |
| 915. Partition Array into Disjoint Intervals | Array | Medium | |
| 916. Word Subsets | Array Hash Table String | Medium | |
| 917. Reverse Only Letters | Two Pointers String | Easy | |
| 918. Maximum Sum Circular Subarray | Queue Array Divide and Conquer Dynamic Programming Monotonic Queue | Medium | |
| 919. Complete Binary Tree Inserter | Tree Breadth-First Search Design Binary Tree | Medium | |
| 920. Number of Music Playlists | Math Dynamic Programming Combinatorics | Hard | |
| 921. Minimum Add to Make Parentheses Valid | Stack Greedy String | Medium | |
| 922. Sort Array By Parity II | Array Two Pointers Sorting | Easy | |
| 923. 3Sum With Multiplicity | Array Hash Table Two Pointers Counting Sorting | Medium | |
| 924. Minimize Malware Spread | Depth-First Search Breadth-First Search Union Find Graph Array Hash Table | Hard | |
| 925. Long Pressed Name | Two Pointers String | Easy | |
| 926. Flip String to Monotone Increasing | String Dynamic Programming | Medium | |
| 927. Three Equal Parts | Array Math | Hard | |
| 928. Minimize Malware Spread II | Depth-First Search Breadth-First Search Union Find Graph Array Hash Table | Hard | |
| 929. Unique Email Addresses | Array Hash Table String | Easy | |
| 930. Binary Subarrays With Sum | Array Hash Table Prefix Sum Sliding Window | Medium | |
| 931. Minimum Falling Path Sum | Array Dynamic Programming Matrix | Medium | |
| 932. Beautiful Array | Array Math Divide and Conquer | Medium | |
| 933. Number of Recent Calls | Design Queue Data Stream | Easy | |
| 934. Shortest Bridge | Depth-First Search Breadth-First Search Array Matrix | Medium | |
| 935. Knight Dialer | Dynamic Programming | Medium | |
| 936. Stamping The Sequence | Stack Greedy Queue String | Hard | |
| 937. Reorder Data in Log Files | Array String Sorting | Medium | |
| 938. Range Sum of BST | Tree Depth-First Search Binary Search Tree Binary Tree | Easy | |
| 939. Minimum Area Rectangle | Geometry Array Hash Table Math Sorting | Medium | |
| 940. Distinct Subsequences II | String Dynamic Programming | Hard | |
| 941. Valid Mountain Array | Array | Easy | |
| 942. DI String Match | Greedy Array Two Pointers String | Easy | |
| 943. Find the Shortest Superstring | Bit Manipulation Array String Dynamic Programming Bitmask | Hard | |
| 944. Delete Columns to Make Sorted | Array String | Easy | |
| 945. Minimum Increment to Make Array Unique | Greedy Array Counting Sorting | Medium | |
| 946. Validate Stack Sequences | Stack Array Simulation | Medium | |
| 947. Most Stones Removed with Same Row or Column | Depth-First Search Union Find Graph Hash Table | Medium | |
| 948. Bag of Tokens | Greedy Array Two Pointers Sorting | Medium | |
| 949. Largest Time for Given Digits | Array String Backtracking Enumeration | Medium | |
| 950. Reveal Cards In Increasing Order | Queue Array Sorting Simulation | Medium | |
| 951. Flip Equivalent Binary Trees | Tree Depth-First Search Binary Tree | Medium | |
| 952. Largest Component Size by Common Factor | Union Find Array Hash Table Math Number Theory | Hard | |
| 953. Verifying an Alien Dictionary | Array Hash Table String | Easy | |
| 954. Array of Doubled Pairs | Greedy Array Hash Table Sorting | Medium | |
| 955. Delete Columns to Make Sorted II | Greedy Array String | Medium | |
| 956. Tallest Billboard | Array Dynamic Programming | Hard | |
| 957. Prison Cells After N Days | Bit Manipulation Array Hash Table Math | Medium | |
| 958. Check Completeness of a Binary Tree | Tree Breadth-First Search Binary Tree | Medium | |
| 959. Regions Cut By Slashes | Depth-First Search Breadth-First Search Union Find Array Hash Table Matrix | Medium | |
| 960. Delete Columns to Make Sorted III | Array String Dynamic Programming | Hard | |
| 961. N-Repeated Element in Size 2N Array | Array Hash Table | Easy | |
| 962. Maximum Width Ramp | Stack Array Two Pointers Monotonic Stack | Medium | |
| 963. Minimum Area Rectangle II | Geometry Array Hash Table Math | Medium | |
| 964. Least Operators to Express Number | Memoization Math Dynamic Programming | Hard | |
| 965. Univalued Binary Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Easy | |
| 966. Vowel Spellchecker | Array Hash Table String | Medium | |
| 967. Numbers With Same Consecutive Differences | Breadth-First Search Backtracking | Medium | |
| 968. Binary Tree Cameras | Tree Depth-First Search Dynamic Programming Binary Tree | Hard | |
| 969. Pancake Sorting | Greedy Array Two Pointers Sorting | Medium | |
| 970. Powerful Integers | Hash Table Math Enumeration | Medium | |
| 971. Flip Binary Tree To Match Preorder Traversal | Tree Depth-First Search Binary Tree | Medium | |
| 972. Equal Rational Numbers | Math String | Hard | |
| 973. K Closest Points to Origin | Geometry Array Math Divide and Conquer Quickselect Sorting Heap (Priority Queue) | Medium | |
| 974. Subarray Sums Divisible by K | Array Hash Table Prefix Sum | Medium | |
| 975. Odd Even Jump | Stack Array Dynamic Programming Ordered Set Sorting Monotonic Stack | Hard | |
| 976. Largest Perimeter Triangle | Greedy Array Math Sorting | Easy | |
| 977. Squares of a Sorted Array | Array Two Pointers Sorting | Easy | |
| 978. Longest Turbulent Subarray | Array Dynamic Programming Sliding Window | Medium | |
| 979. Distribute Coins in Binary Tree | Tree Depth-First Search Binary Tree | Medium | |
| 980. Unique Paths III | Bit Manipulation Array Backtracking Matrix | Hard | |
| 981. Time Based Key-Value Store | Design Hash Table String Binary Search | Medium | |
| 982. Triples with Bitwise AND Equal To Zero | Bit Manipulation Array Hash Table | Hard | |
| 983. Minimum Cost For Tickets | Array Dynamic Programming | Medium | |
| 984. String Without AAA or BBB | Greedy String | Medium | |
| 985. Sum of Even Numbers After Queries | Array Simulation | Medium | |
| 986. Interval List Intersections | Array Two Pointers Line Sweep | Medium | |
| 987. Vertical Order Traversal of a Binary Tree | Tree Depth-First Search Breadth-First Search Hash Table Binary Tree Sorting | Hard | |
| 988. Smallest String Starting From Leaf | Tree Depth-First Search String Backtracking Binary Tree | Medium | |
| 989. Add to Array-Form of Integer | Array Math | Easy | |
| 990. Satisfiability of Equality Equations | Union Find Graph Array String | Medium | |
| 991. Broken Calculator | Greedy Math | Medium | |
| 992. Subarrays with K Different Integers | Array Hash Table Counting Sliding Window | Hard | |
| 993. Cousins in Binary Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Easy | |
| 994. Rotting Oranges | Breadth-First Search Array Matrix | Medium | |
| 995. Minimum Number of K Consecutive Bit Flips | Bit Manipulation Queue Array Prefix Sum Sliding Window | Hard | |
| 996. Number of Squareful Arrays | Bit Manipulation Array Hash Table Math Dynamic Programming Backtracking Bitmask | Hard | |
| 997. Find the Town Judge | Graph Array Hash Table | Easy | |
| 998. Maximum Binary Tree II | Tree Binary Tree | Medium | |
| 999. Available Captures for Rook | Array Matrix Simulation | Easy | |
| 1000. Minimum Cost to Merge Stones | Array Dynamic Programming Prefix Sum | Hard | |
| 1001. Grid Illumination | Array Hash Table | Hard | |
| 1002. Find Common Characters | Array Hash Table String | Easy | |
| 1003. Check If Word Is Valid After Substitutions | Stack String | Medium | |
| 1004. Max Consecutive Ones III | Array Binary Search Prefix Sum Sliding Window | Medium | |
| 1005. Maximize Sum Of Array After K Negations | Greedy Array Sorting | Easy | |
| 1006. Clumsy Factorial | Stack Math Simulation | Medium | |
| 1007. Minimum Domino Rotations For Equal Row | Greedy Array | Medium | |
| 1008. Construct Binary Search Tree from Preorder Traversal | Stack Tree Binary Search Tree Array Binary Tree Monotonic Stack | Medium | |
| 1009. Complement of Base 10 Integer | Bit Manipulation | Easy | |
| 1010. Pairs of Songs With Total Durations Divisible by 60 | Array Hash Table Counting | Medium | |
| 1011. Capacity To Ship Packages Within D Days | Array Binary Search | Medium | |
| 1012. Numbers With Repeated Digits | Math Dynamic Programming | Hard | |
| 1013. Partition Array Into Three Parts With Equal Sum | Greedy Array | Easy | |
| 1014. Best Sightseeing Pair | Array Dynamic Programming | Medium | |
| 1015. Smallest Integer Divisible by K | Hash Table Math | Medium | |
| 1016. Binary String With Substrings Representing 1 To N | Bit Manipulation Hash Table String Sliding Window | Medium | |
| 1017. Convert to Base -2 | Math | Medium | |
| 1018. Binary Prefix Divisible By 5 | Bit Manipulation Array | Easy | |
| 1019. Next Greater Node In Linked List | Stack Array Linked List Monotonic Stack | Medium | |
| 1020. Number of Enclaves | Depth-First Search Breadth-First Search Union Find Array Matrix | Medium | |
| 1021. Remove Outermost Parentheses | Stack String | Easy | |
| 1022. Sum of Root To Leaf Binary Numbers | Tree Depth-First Search Binary Tree | Easy | |
| 1023. Camelcase Matching | Trie Array Two Pointers String String Matching | Medium | |
| 1024. Video Stitching | Greedy Array Dynamic Programming | Medium | |
| 1025. Divisor Game | Brainteaser Math Dynamic Programming Game Theory | Easy | |
| 1026. Maximum Difference Between Node and Ancestor | Tree Depth-First Search Binary Tree | Medium | |
| 1027. Longest Arithmetic Subsequence | Array Hash Table Binary Search Dynamic Programming | Medium | |
| 1028. Recover a Tree From Preorder Traversal | Tree Depth-First Search String Binary Tree | Hard | |
| 1029. Two City Scheduling | Greedy Array Sorting | Medium | |
| 1030. Matrix Cells in Distance Order | Geometry Array Math Matrix Sorting | Easy | |
| 1031. Maximum Sum of Two Non-Overlapping Subarrays | Array Dynamic Programming Sliding Window | Medium | |
| 1032. Stream of Characters | Design Trie Array String Data Stream | Hard | |
| 1033. Moving Stones Until Consecutive | Brainteaser Math | Medium | |
| 1034. Coloring A Border | Depth-First Search Breadth-First Search Array Matrix | Medium | |
| 1035. Uncrossed Lines | Array Dynamic Programming | Medium | |
| 1036. Escape a Large Maze | Depth-First Search Breadth-First Search Array Hash Table | Hard | |
| 1037. Valid Boomerang | Geometry Array Math | Easy | |
| 1038. Binary Search Tree to Greater Sum Tree | Tree Depth-First Search Binary Search Tree Binary Tree | Medium | |
| 1039. Minimum Score Triangulation of Polygon | Array Dynamic Programming | Medium | |
| 1040. Moving Stones Until Consecutive II | Array Math Sorting Sliding Window | Medium | |
| 1041. Robot Bounded In Circle | Math String Simulation | Medium | |
| 1042. Flower Planting With No Adjacent | Depth-First Search Breadth-First Search Graph | Medium | |
| 1043. Partition Array for Maximum Sum | Array Dynamic Programming | Medium | |
| 1044. Longest Duplicate Substring | String Binary Search Suffix Array Sliding Window Hash Function Rolling Hash | Hard | |
| 1046. Last Stone Weight | Array Heap (Priority Queue) | Easy | |
| 1047. Remove All Adjacent Duplicates In String | Stack String | Easy | |
| 1048. Longest String Chain | Array Hash Table Two Pointers String Dynamic Programming Sorting | Medium | |
| 1049. Last Stone Weight II | Array Dynamic Programming | Medium | |
| 1051. Height Checker | Array Counting Sort Sorting | Easy | |
| 1052. Grumpy Bookstore Owner | Array Sliding Window | Medium | |
| 1053. Previous Permutation With One Swap | Greedy Array | Medium | |
| 1054. Distant Barcodes | Greedy Array Hash Table Counting Sorting Heap (Priority Queue) | Medium | |
| 1055. Shortest Way to Form String | Greedy Two Pointers String Binary Search | Medium | |
| 1056. Confusing Number | Math | Easy | |
| 1057. Campus Bikes | Array Sorting Heap (Priority Queue) | Medium | |
| 1058. Minimize Rounding Error to Meet Target | Greedy Array Math String Sorting | Medium | |
| 1059. All Paths from Source Lead to Destination | Graph Topological Sort | Medium | |
| 1060. Missing Element in Sorted Array | Array Binary Search | Medium | |
| 1061. Lexicographically Smallest Equivalent String | Union Find String | Medium | |
| 1062. Longest Repeating Substring | String Binary Search Dynamic Programming Suffix Array Hash Function Rolling Hash | Medium | |
| 1063. Number of Valid Subarrays | Stack Array Monotonic Stack | Hard | |
| 1064. Fixed Point | Array Binary Search | Easy | |
| 1065. Index Pairs of a String | Trie Array String Sorting | Easy | |
| 1066. Campus Bikes II | Bit Manipulation Array Dynamic Programming Backtracking Bitmask | Medium | |
| 1067. Digit Count in Range | Math Dynamic Programming | Hard | |
| 1071. Greatest Common Divisor of Strings | Math String | Easy | |
| 1072. Flip Columns For Maximum Number of Equal Rows | Array Hash Table Matrix | Medium | |
| 1073. Adding Two Negabinary Numbers | Array Math | Medium | |
| 1074. Number of Submatrices That Sum to Target | Array Hash Table Matrix Prefix Sum | Hard | |
| 1078. Occurrences After Bigram | String | Easy | |
| 1079. Letter Tile Possibilities | Hash Table String Backtracking Counting | Medium | |
| 1080. Insufficient Nodes in Root to Leaf Paths | Tree Depth-First Search Binary Tree | Medium | |
| 1081. Smallest Subsequence of Distinct Characters | Stack Greedy String Monotonic Stack | Medium | |
| 1085. Sum of Digits in the Minimum Number | Array Math | Easy | |
| 1086. High Five | Array Hash Table Sorting Heap (Priority Queue) | Easy | |
| 1087. Brace Expansion | Breadth-First Search String Backtracking | Medium | |
| 1088. Confusing Number II | Math Backtracking | Hard | |
| 1089. Duplicate Zeros | Array Two Pointers | Easy | |
| 1090. Largest Values From Labels | Greedy Array Hash Table Counting Sorting | Medium | |
| 1091. Shortest Path in Binary Matrix | Breadth-First Search Array Matrix | Medium | |
| 1092. Shortest Common Supersequence | String Dynamic Programming | Hard | |
| 1093. Statistics from a Large Sample | Array Math Probability and Statistics | Medium | |
| 1094. Car Pooling | Array Prefix Sum Sorting Simulation Heap (Priority Queue) | Medium | |
| 1095. Find in Mountain Array | Array Binary Search Interactive | Hard | |
| 1096. Brace Expansion II | Stack Breadth-First Search String Backtracking | Hard | |
| 1099. Two Sum Less Than K | Array Two Pointers Binary Search Sorting | Easy | |
| 1100. Find K-Length Substrings With No Repeated Characters | Hash Table String Sliding Window | Medium | |
| 1101. The Earliest Moment When Everyone Become Friends | Union Find Array Sorting | Medium | |
| 1102. Path With Maximum Minimum Value | Depth-First Search Breadth-First Search Union Find Array Binary Search Matrix Heap (Priority Queue) | Medium | |
| 1103. Distribute Candies to People | Math Simulation | Easy | |
| 1104. Path In Zigzag Labelled Binary Tree | Tree Math Binary Tree | Medium | |
| 1105. Filling Bookcase Shelves | Array Dynamic Programming | Medium | |
| 1106. Parsing A Boolean Expression | Stack Recursion String | Hard | |
| 1108. Defanging an IP Address | String | Easy | |
| 1109. Corporate Flight Bookings | Array Prefix Sum | Medium | |
| 1110. Delete Nodes And Return Forest | Tree Depth-First Search Array Hash Table Binary Tree | Medium | |
| 1111. Maximum Nesting Depth of Two Valid Parentheses Strings | Stack String | Medium | |
| 1114. Print in Order | Concurrency | Easy | |
| 1115. Print FooBar Alternately | Concurrency | Medium | |
| 1116. Print Zero Even Odd | Concurrency | Medium | |
| 1117. Building H2O | Concurrency | Medium | |
| 1118. Number of Days in a Month | Math | Easy | |
| 1119. Remove Vowels from a String | String | Easy | |
| 1120. Maximum Average Subtree | Tree Depth-First Search Binary Tree | Medium | |
| 1121. Divide Array Into Increasing Sequences | Array Counting | Hard | |
| 1122. Relative Sort Array | Array Hash Table Counting Sort Sorting | Easy | |
| 1123. Lowest Common Ancestor of Deepest Leaves | Tree Depth-First Search Breadth-First Search Hash Table Binary Tree | Medium | |
| 1124. Longest Well-Performing Interval | Stack Array Hash Table Prefix Sum Monotonic Stack | Medium | |
| 1125. Smallest Sufficient Team | Bit Manipulation Array Dynamic Programming Bitmask | Hard | |
| 1128. Number of Equivalent Domino Pairs | Array Hash Table Counting | Easy | |
| 1129. Shortest Path with Alternating Colors | Breadth-First Search Graph | Medium | |
| 1130. Minimum Cost Tree From Leaf Values | Stack Greedy Array Dynamic Programming Monotonic Stack | Medium | |
| 1131. Maximum of Absolute Value Expression | Array Math | Medium | |
| 1133. Largest Unique Number | Array Hash Table Sorting | Easy | |
| 1134. Armstrong Number | Math | Easy | |
| 1135. Connecting Cities With Minimum Cost | Union Find Graph Minimum Spanning Tree Heap (Priority Queue) | Medium | |
| 1136. Parallel Courses | Graph Topological Sort | Medium | |
| 1137. N-th Tribonacci Number | Memoization Math Dynamic Programming | Easy | |
| 1138. Alphabet Board Path | Hash Table String | Medium | |
| 1139. Largest 1-Bordered Square | Array Dynamic Programming Matrix | Medium | |
| 1140. Stone Game II | Array Math Dynamic Programming Game Theory Prefix Sum | Medium | |
| 1143. Longest Common Subsequence | String Dynamic Programming | Medium | |
| 1144. Decrease Elements To Make Array Zigzag | Greedy Array | Medium | |
| 1145. Binary Tree Coloring Game | Tree Depth-First Search Binary Tree | Medium | |
| 1146. Snapshot Array | Design Array Hash Table Binary Search | Medium | |
| 1147. Longest Chunked Palindrome Decomposition | Greedy Two Pointers String Dynamic Programming Hash Function Rolling Hash | Hard | |
| 1150. Check If a Number Is Majority Element in a Sorted Array | Array Binary Search | Easy | |
| 1151. Minimum Swaps to Group All 1's Together | Array Sliding Window | Medium | |
| 1152. Analyze User Website Visit Pattern | Array Hash Table String Sorting | Medium | |
| 1153. String Transforms Into Another String | Graph Hash Table String | Hard | |
| 1154. Day of the Year | Math String | Easy | |
| 1155. Number of Dice Rolls With Target Sum | Dynamic Programming | Medium | |
| 1156. Swap For Longest Repeated Character Substring | Hash Table String Sliding Window | Medium | |
| 1157. Online Majority Element In Subarray | Design Binary Indexed Tree Segment Tree Array Binary Search | Hard | |
| 1160. Find Words That Can Be Formed by Characters | Array Hash Table String Counting | Easy | |
| 1161. Maximum Level Sum of a Binary Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Medium | |
| 1162. As Far from Land as Possible | Breadth-First Search Array Dynamic Programming Matrix | Medium | |
| 1163. Last Substring in Lexicographical Order | Two Pointers String | Hard | |
| 1165. Single-Row Keyboard | Hash Table String | Easy | |
| 1166. Design File System | Design Trie Hash Table String | Medium | |
| 1167. Minimum Cost to Connect Sticks | Greedy Array Heap (Priority Queue) | Medium | |
| 1168. Optimize Water Distribution in a Village | Union Find Graph Minimum Spanning Tree Heap (Priority Queue) | Hard | |
| 1169. Invalid Transactions | Array Hash Table String Sorting | Medium | |
| 1170. Compare Strings by Frequency of the Smallest Character | Array Hash Table String Binary Search Sorting | Medium | |
| 1171. Remove Zero Sum Consecutive Nodes from Linked List | Hash Table Linked List | Medium | |
| 1172. Dinner Plate Stacks | Stack Design Hash Table Heap (Priority Queue) | Hard | |
| 1175. Prime Arrangements | Math | Easy | |
| 1176. Diet Plan Performance | Array Sliding Window | Easy | |
| 1177. Can Make Palindrome from Substring | Bit Manipulation Array Hash Table String Prefix Sum | Medium | |
| 1178. Number of Valid Words for Each Puzzle | Bit Manipulation Trie Array Hash Table String | Hard | |
| 1180. Count Substrings with Only One Distinct Letter | Math String | Easy | |
| 1181. Before and After Puzzle | Array Hash Table String Sorting | Medium | |
| 1182. Shortest Distance to Target Color | Array Binary Search Dynamic Programming | Medium | |
| 1183. Maximum Number of Ones | Greedy Math Sorting Heap (Priority Queue) | Hard | |
| 1184. Distance Between Bus Stops | Array | Easy | |
| 1185. Day of the Week | Math | Easy | |
| 1186. Maximum Subarray Sum with One Deletion | Array Dynamic Programming | Medium | |
| 1187. Make Array Strictly Increasing | Array Binary Search Dynamic Programming Sorting | Hard | |
| 1188. Design Bounded Blocking Queue | Concurrency | Medium | |
| 1189. Maximum Number of Balloons | Hash Table String Counting | Easy | |
| 1190. Reverse Substrings Between Each Pair of Parentheses | Stack String | Medium | |
| 1191. K-Concatenation Maximum Sum | Array Dynamic Programming | Medium | |
| 1192. Critical Connections in a Network | Depth-First Search Graph Biconnected Component | Hard | |
| 1195. Fizz Buzz Multithreaded | Concurrency | Medium | |
| 1196. How Many Apples Can You Put into the Basket | Greedy Array Sorting | Easy | |
| 1197. Minimum Knight Moves | Breadth-First Search | Medium | |
| 1198. Find Smallest Common Element in All Rows | Array Hash Table Binary Search Counting Matrix | Medium | |
| 1199. Minimum Time to Build Blocks | Greedy Array Math Heap (Priority Queue) | Hard | |
| 1200. Minimum Absolute Difference | Array Sorting | Easy | |
| 1201. Ugly Number III | Math Binary Search Combinatorics Number Theory | Medium | |
| 1202. Smallest String With Swaps | Depth-First Search Breadth-First Search Union Find Array Hash Table String Sorting | Medium | |
| 1203. Sort Items by Groups Respecting Dependencies | Depth-First Search Breadth-First Search Graph Topological Sort | Hard | |
| 1206. Design Skiplist | Design Linked List | Hard | |
| 1207. Unique Number of Occurrences | Array Hash Table | Easy | |
| 1208. Get Equal Substrings Within Budget | String Binary Search Prefix Sum Sliding Window | Medium | |
| 1209. Remove All Adjacent Duplicates in String II | Stack String | Medium | |
| 1210. Minimum Moves to Reach Target with Rotations | Breadth-First Search Array Matrix | Hard | |
| 1213. Intersection of Three Sorted Arrays | Array Hash Table Binary Search Counting | Easy | |
| 1214. Two Sum BSTs | Stack Tree Depth-First Search Binary Search Tree Two Pointers Binary Search Binary Tree | Medium | |
| 1215. Stepping Numbers | Breadth-First Search Math Backtracking | Medium | |
| 1216. Valid Palindrome III | String Dynamic Programming | Hard | |
| 1217. Minimum Cost to Move Chips to The Same Position | Greedy Array Math | Easy | |
| 1218. Longest Arithmetic Subsequence of Given Difference | Array Hash Table Dynamic Programming | Medium | |
| 1219. Path with Maximum Gold | Array Backtracking Matrix | Medium | |
| 1220. Count Vowels Permutation | Dynamic Programming | Hard | |
| 1221. Split a String in Balanced Strings | Greedy String Counting | Easy | |
| 1222. Queens That Can Attack the King | Array Matrix Simulation | Medium | |
| 1223. Dice Roll Simulation | Array Dynamic Programming | Hard | |
| 1224. Maximum Equal Frequency | Array Hash Table | Hard | |
| 1226. The Dining Philosophers | Concurrency | Medium | |
| 1227. Airplane Seat Assignment Probability | Brainteaser Math Dynamic Programming Probability and Statistics | Medium | |
| 1228. Missing Number In Arithmetic Progression | Array Math | Easy | |
| 1229. Meeting Scheduler | Array Two Pointers Sorting | Medium | |
| 1230. Toss Strange Coins | Array Math Dynamic Programming Probability and Statistics | Medium | |
| 1231. Divide Chocolate | Array Binary Search | Hard | |
| 1232. Check If It Is a Straight Line | Geometry Array Math | Easy | |
| 1233. Remove Sub-Folders from the Filesystem | Depth-First Search Trie Array String | Medium | |
| 1234. Replace the Substring for Balanced String | String Sliding Window | Medium | |
| 1235. Maximum Profit in Job Scheduling | Array Binary Search Dynamic Programming Sorting | Hard | |
| 1236. Web Crawler | Depth-First Search Breadth-First Search String Interactive | Medium | |
| 1237. Find Positive Integer Solution for a Given Equation | Math Two Pointers Binary Search Interactive | Medium | |
| 1238. Circular Permutation in Binary Representation | Bit Manipulation Math Backtracking | Medium | |
| 1239. Maximum Length of a Concatenated String with Unique Characters | Bit Manipulation Array String Backtracking | Medium | |
| 1240. Tiling a Rectangle with the Fewest Squares | Backtracking | Hard | |
| 1242. Web Crawler Multithreaded | Depth-First Search Breadth-First Search Concurrency | Medium | |
| 1243. Array Transformation | Array Simulation | Easy | |
| 1244. Design A Leaderboard | Design Hash Table Sorting | Medium | |
| 1245. Tree Diameter | Tree Depth-First Search Breadth-First Search Graph Topological Sort | Medium | |
| 1246. Palindrome Removal | Array Dynamic Programming | Hard | |
| 1247. Minimum Swaps to Make Strings Equal | Greedy Math String | Medium | |
| 1248. Count Number of Nice Subarrays | Array Hash Table Math Prefix Sum Sliding Window | Medium | |
| 1249. Minimum Remove to Make Valid Parentheses | Stack String | Medium | |
| 1250. Check If It Is a Good Array | Array Math Number Theory | Hard | |
| 1252. Cells with Odd Values in a Matrix | Array Math Simulation | Easy | |
| 1253. Reconstruct a 2-Row Binary Matrix | Greedy Array Matrix | Medium | |
| 1254. Number of Closed Islands | Depth-First Search Breadth-First Search Union Find Array Matrix | Medium | |
| 1255. Maximum Score Words Formed by Letters | Bit Manipulation Array String Dynamic Programming Backtracking Bitmask | Hard | |
| 1256. Encode Number | Bit Manipulation Math String | Medium | |
| 1257. Smallest Common Region | Tree Depth-First Search Breadth-First Search Array Hash Table String | Medium | |
| 1258. Synonymous Sentences | Sort Union Find Array Hash Table String Backtracking | Medium | |
| 1259. Handshakes That Don't Cross | Math Dynamic Programming | Hard | |
| 1260. Shift 2D Grid | Array Matrix Simulation | Easy | |
| 1261. Find Elements in a Contaminated Binary Tree | Tree Depth-First Search Breadth-First Search Design Hash Table Binary Tree | Medium | |
| 1262. Greatest Sum Divisible by Three | Greedy Array Dynamic Programming Sorting | Medium | |
| 1263. Minimum Moves to Move a Box to Their Target Location | Breadth-First Search Array Matrix Heap (Priority Queue) | Hard | |
| 1265. Print Immutable Linked List in Reverse | Stack Recursion Linked List Two Pointers | Medium | |
| 1266. Minimum Time Visiting All Points | Geometry Array Math | Easy | |
| 1267. Count Servers that Communicate | Depth-First Search Breadth-First Search Union Find Array Counting Matrix | Medium | |
| 1268. Search Suggestions System | Trie Array String Binary Search Sorting Heap (Priority Queue) | Medium | |
| 1269. Number of Ways to Stay in the Same Place After Some Steps | Dynamic Programming | Hard | |
| 1271. Hexspeak | Math String | Easy | |
| 1272. Remove Interval | Array | Medium | |
| 1273. Delete Tree Nodes | Tree Depth-First Search Breadth-First Search Array | Medium | |
| 1274. Number of Ships in a Rectangle | Array Divide and Conquer Interactive | Hard | |
| 1275. Find Winner on a Tic Tac Toe Game | Array Hash Table Matrix Simulation | Easy | |
| 1276. Number of Burgers with No Waste of Ingredients | Math | Medium | |
| 1277. Count Square Submatrices with All Ones | Array Dynamic Programming Matrix | Medium | |
| 1278. Palindrome Partitioning III | String Dynamic Programming | Hard | |
| 1279. Traffic Light Controlled Intersection | Concurrency | Easy | |
| 1281. Subtract the Product and Sum of Digits of an Integer | Math | Easy | |
| 1282. Group the People Given the Group Size They Belong To | Greedy Array Hash Table | Medium | |
| 1283. Find the Smallest Divisor Given a Threshold | Array Binary Search | Medium | |
| 1284. Minimum Number of Flips to Convert Binary Matrix to Zero Matrix | Bit Manipulation Breadth-First Search Array Hash Table Matrix | Hard | |
| 1286. Iterator for Combination | Design String Backtracking Iterator | Medium | |
| 1287. Element Appearing More Than 25% In Sorted Array | Array | Easy | |
| 1288. Remove Covered Intervals | Array Sorting | Medium | |
| 1289. Minimum Falling Path Sum II | Array Dynamic Programming Matrix | Hard | |
| 1290. Convert Binary Number in a Linked List to Integer | Linked List Math | Easy | |
| 1291. Sequential Digits | Enumeration | Medium | |
| 1292. Maximum Side Length of a Square with Sum Less than or Equal to Threshold | Array Binary Search Matrix Prefix Sum | Medium | |
| 1293. Shortest Path in a Grid with Obstacles Elimination | Breadth-First Search Array Matrix | Hard | |
| 1295. Find Numbers with Even Number of Digits | Array Math | Easy | |
| 1296. Divide Array in Sets of K Consecutive Numbers | Greedy Array Hash Table Sorting | Medium | |
| 1297. Maximum Number of Occurrences of a Substring | Hash Table String Sliding Window | Medium | |
| 1298. Maximum Candies You Can Get from Boxes | Breadth-First Search Graph Array | Hard | |
| 1299. Replace Elements with Greatest Element on Right Side | Array | Easy | |
| 1300. Sum of Mutated Array Closest to Target | Array Binary Search Sorting | Medium | |
| 1301. Number of Paths with Max Score | Array Dynamic Programming Matrix | Hard | |
| 1302. Deepest Leaves Sum | Tree Depth-First Search Breadth-First Search Binary Tree | Medium | |
| 1304. Find N Unique Integers Sum up to Zero | Array Math | Easy | |
| 1305. All Elements in Two Binary Search Trees | Tree Depth-First Search Binary Search Tree Binary Tree Sorting | Medium | |
| 1306. Jump Game III | Depth-First Search Breadth-First Search Array | Medium | |
| 1307. Verbal Arithmetic Puzzle | Array Math String Backtracking | Hard | |
| 1309. Decrypt String from Alphabet to Integer Mapping | String | Easy | |
| 1310. XOR Queries of a Subarray | Bit Manipulation Array Prefix Sum | Medium | |
| 1311. Get Watched Videos by Your Friends | Breadth-First Search Graph Array Hash Table Sorting | Medium | |
| 1312. Minimum Insertion Steps to Make a String Palindrome | String Dynamic Programming | Hard | |
| 1313. Decompress Run-Length Encoded List | Array | Easy | |
| 1314. Matrix Block Sum | Array Matrix Prefix Sum | Medium | |
| 1315. Sum of Nodes with Even-Valued Grandparent | Tree Depth-First Search Breadth-First Search Binary Tree | Medium | |
| 1316. Distinct Echo Substrings | Trie String Hash Function Rolling Hash | Hard | |
| 1317. Convert Integer to the Sum of Two No-Zero Integers | Math | Easy | |
| 1318. Minimum Flips to Make a OR b Equal to c | Bit Manipulation | Medium | |
| 1319. Number of Operations to Make Network Connected | Depth-First Search Breadth-First Search Union Find Graph | Medium | |
| 1320. Minimum Distance to Type a Word Using Two Fingers | String Dynamic Programming | Hard | |
| 1323. Maximum 69 Number | Greedy Math | Easy | |
| 1324. Print Words Vertically | Array String Simulation | Medium | |
| 1325. Delete Leaves With a Given Value | Tree Depth-First Search Binary Tree | Medium | |
| 1326. Minimum Number of Taps to Open to Water a Garden | Greedy Array Dynamic Programming | Hard | |
| 1328. Break a Palindrome | Greedy String | Medium | |
| 1329. Sort the Matrix Diagonally | Array Matrix Sorting | Medium | |
| 1330. Reverse Subarray To Maximize Array Value | Greedy Array Math | Hard | |
| 1331. Rank Transform of an Array | Array Hash Table Sorting | Easy | |
| 1332. Remove Palindromic Subsequences | Two Pointers String | Easy | |
| 1333. Filter Restaurants by Vegan-Friendly, Price and Distance | Array Sorting | Medium | |
| 1334. Find the City With the Smallest Number of Neighbors at a Threshold Distance | Graph Dynamic Programming Shortest Path | Medium | |
| 1335. Minimum Difficulty of a Job Schedule | Array Dynamic Programming | Hard | |
| 1337. The K Weakest Rows in a Matrix | Array Binary Search Matrix Sorting Heap (Priority Queue) | Easy | |
| 1338. Reduce Array Size to The Half | Greedy Array Hash Table Sorting Heap (Priority Queue) | Medium | |
| 1339. Maximum Product of Splitted Binary Tree | Tree Depth-First Search Binary Tree | Medium | |
| 1340. Jump Game V | Array Dynamic Programming Sorting | Hard | |
| 1342. Number of Steps to Reduce a Number to Zero | Bit Manipulation Math | Easy | |
| 1343. Number of Sub-arrays of Size K and Average Greater than or Equal to Threshold | Array Sliding Window | Medium | |
| 1344. Angle Between Hands of a Clock | Math | Medium | |
| 1345. Jump Game IV | Breadth-First Search Array Hash Table | Hard | |
| 1346. Check If N and Its Double Exist | Array Hash Table Two Pointers Binary Search Sorting | Easy | |
| 1347. Minimum Number of Steps to Make Two Strings Anagram | Hash Table String Counting | Medium | |
| 1348. Tweet Counts Per Frequency | Design Hash Table Binary Search Ordered Set Sorting | Medium | |
| 1349. Maximum Students Taking Exam | Bit Manipulation Array Dynamic Programming Bitmask Matrix | Hard | |
| 1351. Count Negative Numbers in a Sorted Matrix | Array Binary Search Matrix | Easy | |
| 1352. Product of the Last K Numbers | Design Array Math Data Stream Prefix Sum | Medium | |
| 1353. Maximum Number of Events That Can Be Attended | Greedy Array Sorting Heap (Priority Queue) | Medium | |
| 1354. Construct Target Array With Multiple Sums | Array Heap (Priority Queue) | Hard | |
| 1356. Sort Integers by The Number of 1 Bits | Bit Manipulation Array Counting Sorting | Easy | |
| 1357. Apply Discount Every n Orders | Design Array Hash Table | Medium | |
| 1358. Number of Substrings Containing All Three Characters | Hash Table String Sliding Window | Medium | |
| 1359. Count All Valid Pickup and Delivery Options | Math Dynamic Programming Combinatorics | Hard | |
| 1360. Number of Days Between Two Dates | Math String | Easy | |
| 1361. Validate Binary Tree Nodes | Tree Depth-First Search Breadth-First Search Union Find Graph Binary Tree | Medium | |
| 1362. Closest Divisors | Math | Medium | |
| 1363. Largest Multiple of Three | Greedy Array Math Dynamic Programming Sorting | Hard | |
| 1365. How Many Numbers Are Smaller Than the Current Number | Array Hash Table Counting Sort Sorting | Easy | |
| 1366. Rank Teams by Votes | Array Hash Table String Counting Sorting | Medium | |
| 1367. Linked List in Binary Tree | Tree Depth-First Search Linked List Binary Tree | Medium | |
| 1368. Minimum Cost to Make at Least One Valid Path in a Grid | Breadth-First Search Graph Array Matrix Shortest Path Heap (Priority Queue) | Hard | |
| 1370. Increasing Decreasing String | Hash Table String Counting | Easy | |
| 1371. Find the Longest Substring Containing Vowels in Even Counts | Bit Manipulation Hash Table String Prefix Sum | Medium | |
| 1372. Longest ZigZag Path in a Binary Tree | Tree Depth-First Search Dynamic Programming Binary Tree | Medium | |
| 1373. Maximum Sum BST in Binary Tree | Tree Depth-First Search Binary Search Tree Dynamic Programming Binary Tree | Hard | |
| 1374. Generate a String With Characters That Have Odd Counts | String | Easy | |
| 1375. Number of Times Binary String Is Prefix-Aligned | Array | Medium | |
| 1376. Time Needed to Inform All Employees | Tree Depth-First Search Breadth-First Search | Medium | |
| 1377. Frog Position After T Seconds | Tree Depth-First Search Breadth-First Search Graph | Hard | |
| 1379. Find a Corresponding Node of a Binary Tree in a Clone of That Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Easy | |
| 1380. Lucky Numbers in a Matrix | Array Matrix | Easy | |
| 1381. Design a Stack With Increment Operation | Stack Design Array | Medium | |
| 1382. Balance a Binary Search Tree | Greedy Tree Depth-First Search Binary Search Tree Divide and Conquer Binary Tree | Medium | |
| 1383. Maximum Performance of a Team | Greedy Array Sorting Heap (Priority Queue) | Hard | |
| 1385. Find the Distance Value Between Two Arrays | Array Two Pointers Binary Search Sorting | Easy | |
| 1386. Cinema Seat Allocation | Greedy Bit Manipulation Array Hash Table | Medium | |
| 1387. Sort Integers by The Power Value | Memoization Dynamic Programming Sorting | Medium | |
| 1388. Pizza With 3n Slices | Greedy Array Dynamic Programming Heap (Priority Queue) | Hard | |
| 1389. Create Target Array in the Given Order | Array Simulation | Easy | |
| 1390. Four Divisors | Array Math | Medium | |
| 1391. Check if There is a Valid Path in a Grid | Depth-First Search Breadth-First Search Union Find Array Matrix | Medium | |
| 1392. Longest Happy Prefix | String String Matching Hash Function Rolling Hash | Hard | |
| 1394. Find Lucky Integer in an Array | Array Hash Table Counting | Easy | |
| 1395. Count Number of Teams | Binary Indexed Tree Segment Tree Array Dynamic Programming | Medium | |
| 1396. Design Underground System | Design Hash Table String | Medium | |
| 1397. Find All Good Strings | String Dynamic Programming String Matching | Hard | |
| 1399. Count Largest Group | Hash Table Math | Easy | |
| 1400. Construct K Palindrome Strings | Greedy Hash Table String Counting | Medium | |
| 1401. Circle and Rectangle Overlapping | Geometry Math | Medium | |
| 1402. Reducing Dishes | Greedy Array Dynamic Programming Sorting | Hard | |
| 1403. Minimum Subsequence in Non-Increasing Order | Greedy Array Sorting | Easy | |
| 1404. Number of Steps to Reduce a Number in Binary Representation to One | Bit Manipulation String Simulation | Medium | |
| 1405. Longest Happy String | Greedy String Heap (Priority Queue) | Medium | |
| 1406. Stone Game III | Array Math Dynamic Programming Game Theory | Hard | |
| 1408. String Matching in an Array | Array String String Matching | Easy | |
| 1409. Queries on a Permutation With Key | Binary Indexed Tree Array Simulation | Medium | |
| 1410. HTML Entity Parser | Hash Table String | Medium | |
| 1411. Number of Ways to Paint N × 3 Grid | Dynamic Programming | Hard | |
| 1413. Minimum Value to Get Positive Step by Step Sum | Array Prefix Sum | Easy | |
| 1414. Find the Minimum Number of Fibonacci Numbers Whose Sum Is K | Greedy Math | Medium | |
| 1415. The k-th Lexicographical String of All Happy Strings of Length n | String Backtracking | Medium | |
| 1416. Restore The Array | String Dynamic Programming | Hard | |
| 1417. Reformat The String | String | Easy | |
| 1418. Display Table of Food Orders in a Restaurant | Array Hash Table String Ordered Set Sorting | Medium | |
| 1419. Minimum Number of Frogs Croaking | String Counting | Medium | |
| 1420. Build Array Where You Can Find The Maximum Exactly K Comparisons | Dynamic Programming Prefix Sum | Hard | |
| 1422. Maximum Score After Splitting a String | String Prefix Sum | Easy | |
| 1423. Maximum Points You Can Obtain from Cards | Array Prefix Sum Sliding Window | Medium | |
| 1424. Diagonal Traverse II | Array Sorting Heap (Priority Queue) | Medium | |
| 1425. Constrained Subsequence Sum | Queue Array Dynamic Programming Sliding Window Monotonic Queue Heap (Priority Queue) | Hard | |
| 1426. Counting Elements | Array Hash Table | Easy | |
| 1427. Perform String Shifts | Array Math String | Easy | |
| 1428. Leftmost Column with at Least a One | Array Binary Search Interactive Matrix | Medium | |
| 1429. First Unique Number | Design Queue Array Hash Table Data Stream | Medium | |
| 1430. Check If a String Is a Valid Sequence from Root to Leaves Path in a Binary Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Medium | |
| 1431. Kids With the Greatest Number of Candies | Array | Easy | |
| 1432. Max Difference You Can Get From Changing an Integer | Greedy Math | Medium | |
| 1433. Check If a String Can Break Another String | Greedy String Sorting | Medium | |
| 1434. Number of Ways to Wear Different Hats to Each Other | Bit Manipulation Array Dynamic Programming Bitmask | Hard | |
| 1436. Destination City | Array Hash Table String | Easy | |
| 1437. Check If All 1's Are at Least Length K Places Away | Array | Easy | |
| 1438. Longest Continuous Subarray With Absolute Diff Less Than or Equal to Limit | Queue Array Ordered Set Sliding Window Monotonic Queue Heap (Priority Queue) | Medium | |
| 1439. Find the Kth Smallest Sum of a Matrix With Sorted Rows | Array Binary Search Matrix Heap (Priority Queue) | Hard | |
| 1441. Build an Array With Stack Operations | Stack Array Simulation | Medium | |
| 1442. Count Triplets That Can Form Two Arrays of Equal XOR | Bit Manipulation Array Hash Table Math Prefix Sum | Medium | |
| 1443. Minimum Time to Collect All Apples in a Tree | Tree Depth-First Search Breadth-First Search Hash Table | Medium | |
| 1444. Number of Ways of Cutting a Pizza | Memoization Array Dynamic Programming Matrix Prefix Sum | Hard | |
| 1446. Consecutive Characters | String | Easy | |
| 1447. Simplified Fractions | Math String Number Theory | Medium | |
| 1448. Count Good Nodes in Binary Tree | Tree Depth-First Search Breadth-First Search Binary Tree | Medium | |
| 1449. Form Largest Integer With Digits That Add up to Target | Array Dynamic Programming | Hard | |
| 1450. Number of Students Doing Homework at a Given Time | Array | Easy | |
| 1451. Rearrange Words in a Sentence | String Sorting | Medium | |
| 1452. People Whose List of Favorite Companies Is Not a Subset of Another List | Array Hash Table String | Medium | |
| 1453. Maximum Number of Darts Inside of a Circular Dartboard | Geometry Array Math | Hard | |
| 1455. Check If a Word Occurs As a Prefix of Any Word in a Sentence | Two Pointers String String Matching | Easy | |
| 1456. Maximum Number of Vowels in a Substring of Given Length | String Sliding Window | Medium | |
| 1457. Pseudo-Palindromic Paths in a Binary Tree | Bit Manipulation Tree Depth-First Search Breadth-First Search Binary Tree | Medium | |
| 1458. Max Dot Product of Two Subsequences | Array Dynamic Programming | Hard | |
| 1460. Make Two Arrays Equal by Reversing Subarrays | Array Hash Table Sorting | Easy | |
| 1461. Check If a String Contains All Binary Codes of Size K | Bit Manipulation Hash Table String Hash Function Rolling Hash | Medium | |
| 1462. Course Schedule IV | Depth-First Search Breadth-First Search Graph Topological Sort | Medium | |
| 1463. Cherry Pickup II | Array Dynamic Programming Matrix | Hard | |
| 1464. Maximum Product of Two Elements in an Array | Array Sorting Heap (Priority Queue) | Easy | |
| 1465. Maximum Area of a Piece of Cake After Horizontal and Vertical Cuts | Greedy Array Sorting | Medium | |
| 1466. Reorder Routes to Make All Paths Lead to the City Zero | Depth-First Search Breadth-First Search Graph | Medium | |
| 1467. Probability of a Two Boxes Having The Same Number of Distinct Balls | Array Math Dynamic Programming Backtracking Combinatorics Probability and Statistics | Hard | |
| 1469. Find All The Lonely Nodes | Tree Depth-First Search Breadth-First Search Binary Tree | Easy | |
| 1470. Shuffle the Array | Array | Easy | |
| 1471. The k Strongest Values in an Array | Array Two Pointers Sorting | Medium | |
| 1472. Design Browser History | Stack Design Array Linked List Data Stream Doubly-Linked List | Medium | |
| 1473. Paint House III | Array Dynamic Programming | Hard | |
| 1474. Delete N Nodes After M Nodes of a Linked List | Linked List | Easy | |
| 1475. Final Prices With a Special Discount in a Shop | Stack Array Monotonic Stack | Easy | |
| 1476. Subrectangle Queries | Design Array Matrix | Medium | |
| 1477. Find Two Non-overlapping Sub-arrays Each With Target Sum | Array Hash Table Binary Search Dynamic Programming Sliding Window | Medium | |
| 1478. Allocate Mailboxes | Array Math Dynamic Programming Sorting | Hard | |
| 1480. Running Sum of 1d Array | Array Prefix Sum | Easy | |
| 1481. Least Number of Unique Integers after K Removals | Greedy Array Hash Table Counting Sorting | Medium | |
| 1482. Minimum Number of Days to Make m Bouquets | Array Binary Search | Medium | |
| 1483. Kth Ancestor of a Tree Node | Tree Depth-First Search Breadth-First Search Design Binary Search Dynamic Programming | Hard | |
| 1485. Clone Binary Tree With Random Pointer | Tree Depth-First Search Breadth-First Search Hash Table Binary Tree | Medium | |
| 1486. XOR Operation in an Array | Bit Manipulation Math | Easy | |
| 1487. Making File Names Unique | Array Hash Table String | Medium | |
| 1488. Avoid Flood in The City | Greedy Array Hash Table Binary Search Heap (Priority Queue) | Medium | |
| 1489. Find Critical and Pseudo-Critical Edges in Minimum Spanning Tree | Union Find Graph Minimum Spanning Tree Sorting Strongly Connected Component | Hard | |
| 1490. Clone N-ary Tree | Tree Depth-First Search Breadth-First Search Hash Table | Medium | |
| 1491. Average Salary Excluding the Minimum and Maximum Salary | Array Sorting | Easy | |
| 1492. The kth Factor of n | Math Number Theory | Medium | |
| 1493. Longest Subarray of 1's After Deleting One Element | Array Dynamic Programming Sliding Window | Medium | |
| 1494. Parallel Courses II | Bit Manipulation Graph Dynamic Programming Bitmask | Hard | |
| 1496. Path Crossing | Hash Table String | Easy | |
| 1497. Check If Array Pairs Are Divisible by k | Array Hash Table Counting | Medium | |
| 1498. Number of Subsequences That Satisfy the Given Sum Condition | Array Two Pointers Binary Search Sorting | Medium | |
| 1499. Max Value of Equation | Queue Array Sliding Window Monotonic Queue Heap (Priority Queue) | Hard | |
| 1500. Design a File Sharing System | Design Hash Table Data Stream Sorting Heap (Priority Queue) | Medium | |
| 1502. Can Make Arithmetic Progression From Sequence | Array Sorting | Easy | |
| 1503. Last Moment Before All Ants Fall Out of a Plank | Brainteaser Array Simulation | Medium | |
| 1504. Count Submatrices With All Ones | Stack Array Dynamic Programming Matrix Monotonic Stack | Medium | |
| 1505. Minimum Possible Integer After at Most K Adjacent Swaps On Digits | Greedy Binary Indexed Tree Segment Tree String | Hard | |
| 1506. Find Root of N-Ary Tree | Bit Manipulation Tree Depth-First Search Hash Table | Medium | |
| 1507. Reformat Date | String | Easy | |
| 1508. Range Sum of Sorted Subarray Sums | Array Two Pointers Binary Search Prefix Sum Sorting | Medium | |
| 1509. Minimum Difference Between Largest and Smallest Value in Three Moves | Greedy Array Sorting | Medium | |
| 1510. Stone Game IV | Math Dynamic Programming Game Theory | Hard | |
| 1512. Number of Good Pairs | Array Hash Table Math Counting | Easy | |
| 1513. Number of Substrings With Only 1s | Math String | Medium | |
| 1514. Path with Maximum Probability | Graph Array Shortest Path Heap (Priority Queue) | Medium | |
| 1515. Best Position for a Service Centre | Geometry Array Math Randomized | Hard | |
| 1516. Move Sub-Tree of N-Ary Tree | Tree Depth-First Search | Hard | |
| 1518. Water Bottles | Math Simulation | Easy | |
| 1519. Number of Nodes in the Sub-Tree With the Same Label | Tree Depth-First Search Breadth-First Search Hash Table Counting | Medium | |
| 1520. Maximum Number of Non-Overlapping Substrings | Greedy String | Hard | |
| 1521. Find a Value of a Mysterious Function Closest to Target | Bit Manipulation Segment Tree Array Binary Search | Hard | |
| 1522. Diameter of N-Ary Tree | Tree Depth-First Search | Medium | |
| 1523. Count Odd Numbers in an Interval Range | Math | Easy | |
| 1524. Number of Sub-arrays With Odd Sum | Array Math Dynamic Programming Prefix Sum | Medium | |
| 1525. Number of Good Ways to Split a String | Bit Manipulation Hash Table String Dynamic Programming | Medium | |
| 1526. Minimum Number of Increments on Subarrays to Form a Target Array | Stack Greedy Array Dynamic Programming Monotonic Stack | Hard | |
| 1528. Shuffle String | Array String | Easy | |
| 1529. Minimum Suffix Flips | Greedy String | Medium | |
| 1530. Number of Good Leaf Nodes Pairs | Tree Depth-First Search Binary Tree | Medium | |
| 1531. String Compression II | String Dynamic Programming | Hard | |
| 1533. Find the Index of the Large Integer | Array Binary Search Interactive | Medium | |
| 1534. Count Good Triplets | Array Enumeration | Easy | |
| 1535. Find the Winner of an Array Game | Array Simulation | Medium | |
| 1536. Minimum Swaps to Arrange a Binary Grid | Greedy Array Matrix | Medium | |
| 1537. Get the Maximum Score | Greedy Array Two Pointers Dynamic Programming | Hard | |
| 1538. Guess the Majority in a Hidden Array | Array Math Interactive | Medium | |
| 1539. Kth Missing Positive Number | Array Binary Search | Easy | |
| 1540. Can Convert String in K Moves | Hash Table String | Medium | |
| 1541. Minimum Insertions to Balance a Parentheses String | Stack Greedy String | Medium | |
| 1542. Find Longest Awesome Substring | Bit Manipulation Hash Table String | Hard | |
| 1544. Make The String Great | Stack String | Easy | |
| 1545. Find Kth Bit in Nth Binary String | Recursion String Simulation | Medium | |
| 1546. Maximum Number of Non-Overlapping Subarrays With Sum Equals Target | Greedy Array Hash Table Prefix Sum | Medium | |
| 1547. Minimum Cost to Cut a Stick | Array Dynamic Programming Sorting | Hard | |
| 1548. The Most Similar Path in a Graph | Graph Dynamic Programming | Hard | |
| 1550. Three Consecutive Odds | Array | Easy | |
| 1551. Minimum Operations to Make Array Equal | Math | Medium | |
| 1552. Magnetic Force Between Two Balls | Array Binary Search Sorting | Medium | |
| 1553. Minimum Number of Days to Eat N Oranges | Memoization Dynamic Programming | Hard | |
| 1554. Strings Differ by One Character | Hash Table String Hash Function Rolling Hash | Medium | |
| 1556. Thousand Separator | String | Easy | |
| 1557. Minimum Number of Vertices to Reach All Nodes | Graph | Medium | |
| 1558. Minimum Numbers of Function Calls to Make Target Array | Greedy Bit Manipulation Array | Medium | |
| 1559. Detect Cycles in 2D Grid | Depth-First Search Breadth-First Search Union Find Array Matrix | Medium | |
| 1560. Most Visited Sector in a Circular Track | Array Simulation | Easy | |
| 1561. Maximum Number of Coins You Can Get | Greedy Array Math Game Theory Sorting | Medium | |
| 1562. Find Latest Group of Size M | Array Hash Table Binary Search Simulation | Medium | |
| 1563. Stone Game V | Array Math Dynamic Programming Game Theory | Hard | |
| 1564. Put Boxes Into the Warehouse I | Greedy Array Sorting | Medium | |
| 1566. Detect Pattern of Length M Repeated K or More Times | Array Enumeration | Easy | |
| 1567. Maximum Length of Subarray With Positive Product | Greedy Array Dynamic Programming | Medium | |
| 1568. Minimum Number of Days to Disconnect Island | Depth-First Search Breadth-First Search Array Matrix Strongly Connected Component | Hard | |
| 1569. Number of Ways to Reorder Array to Get Same BST | Tree Union Find Binary Search Tree Memoization Array Math Divide and Conquer Dynamic Programming Binary Tree Combinatorics | Hard | |
| 1570. Dot Product of Two Sparse Vectors | Design Array Hash Table Two Pointers | Medium | |
| 1572. Matrix Diagonal Sum | Array Matrix | Easy | |
| 1573. Number of Ways to Split a String | Math String | Medium | |
| 1574. Shortest Subarray to be Removed to Make Array Sorted | Stack Array Two Pointers Binary Search Monotonic Stack | Medium | |
| 1575. Count All Possible Routes | Memoization Array Dynamic Programming | Hard | |
| 1576. Replace All 's to Avoid Consecutive Repeating Characters | String | Easy | |
| 1577. Number of Ways Where Square of Number Is Equal to Product of Two Numbers | Array Hash Table Math Two Pointers | Medium | |
| 1578. Minimum Time to Make Rope Colorful | Greedy Array String Dynamic Programming | Medium | |
| 1579. Remove Max Number of Edges to Keep Graph Fully Traversable | Union Find Graph | Hard | |
| 1580. Put Boxes Into the Warehouse II | Greedy Array Sorting | Medium | |
| 1582. Special Positions in a Binary Matrix | Array Matrix | Easy | |
| 1583. Count Unhappy Friends | Array Simulation | Medium | |
| 1584. Min Cost to Connect All Points | Union Find Graph Array Minimum Spanning Tree | Medium | |
| 1585. Check If String Is Transformable With Substring Sort Operations | Greedy String Sorting | Hard | |
| 1586. Binary Search Tree Iterator II | Stack Tree Design Binary Search Tree Binary Tree Iterator | Medium | |
| 1588. Sum of All Odd Length Subarrays | Array Math Prefix Sum | Easy | |
| 1589. Maximum Sum Obtained of Any Permutation | Greedy Array Prefix Sum Sorting | Medium | |
| 1590. Make Sum Divisible by P | Array Hash Table Prefix Sum | Medium | |
| 1591. Strange Printer II | Graph Topological Sort Array Matrix | Hard | |
| 1592. Rearrange Spaces Between Words | String | Easy | |
| 1593. Split a String Into the Max Number of Unique Substrings | Hash Table String Backtracking | Medium | |
| 1594. Maximum Non Negative Product in a Matrix | Array Dynamic Programming Matrix | Medium | |
| 1595. Minimum Cost to Connect Two Groups of Points | Bit Manipulation Array Dynamic Programming Bitmask Matrix | Hard | |
| 1597. Build Binary Expression Tree From Infix Expression | Stack Tree String Binary Tree | Hard | |
| 1598. Crawler Log Folder | Stack Array String | Easy | |
| 1599. Maximum Profit of Operating a Centennial Wheel | Array Simulation | Medium | |
| 1600. Throne Inheritance | Tree Depth-First Search Design Hash Table | Medium | |
| 1601. Maximum Number of Achievable Transfer Requests | Bit Manipulation Array Backtracking Enumeration | Hard | |
| 1602. Find Nearest Right Node in Binary Tree | Tree Breadth-First Search Binary Tree | Medium | |
| 1603. Design Parking System | Design Counting Simulation | Easy | |
| 1604. Alert Using Same Key-Card Three or More Times in a One Hour Period | Array Hash Table String Sorting | Medium | |
| 1605. Find Valid Matrix Given Row and Column Sums | Greedy Array Matrix | Medium | |
| 1606. Find Servers That Handled Most Number of Requests | Greedy Array Ordered Set Heap (Priority Queue) | Hard | |
| 1608. Special Array With X Elements Greater Than or Equal X | Array Binary Search Sorting | Easy | |
| 1609. Even Odd Tree | Tree Breadth-First Search Binary Tree | Medium | |
| 1610. Maximum Number of Visible Points | Geometry Array Math Sorting Sliding Window | Hard | |
| 1611. Minimum One Bit Operations to Make Integers Zero | Bit Manipulation Memoization Dynamic Programming | Hard | |
| 1612. Check If Two Expression Trees are Equivalent | Tree Depth-First Search Hash Table Binary Tree Counting | Medium | |
| 1614. Maximum Nesting Depth of the Parentheses | Stack String | Easy | |
| 1615. Maximal Network Rank | Graph | Medium | |
| 1616. Split Two Strings to Make Palindrome | Two Pointers String | Medium | |
| 1617. Count Subtrees With Max Distance Between Cities | Bit Manipulation Tree Dynamic Programming Bitmask Enumeration | Hard | |
| 1618. Maximum Font to Fit a Sentence in a Screen | Array String Binary Search Interactive | Medium | |
| 1619. Mean of Array After Removing Some Elements | Array Sorting | Easy | |
| 1620. Coordinate With Maximum Network Quality | Array Enumeration | Medium | |
| 1621. Number of Sets of K Non-Overlapping Line Segments | Math Dynamic Programming Combinatorics | Medium | |
| 1622. Fancy Sequence | Design Segment Tree Math | Hard | |
| 1624. Largest Substring Between Two Equal Characters | Hash Table String | Easy | |
| 1625. Lexicographically Smallest String After Applying Operations | Depth-First Search Breadth-First Search String Enumeration | Medium | |
| 1626. Best Team With No Conflicts | Array Dynamic Programming Sorting | Medium | |
| 1627. Graph Connectivity With Threshold | Union Find Array Math Number Theory | Hard | |
| 1628. Design an Expression Tree With Evaluate Function | Stack Tree Design Array Math Binary Tree | Medium | |
| 1629. Slowest Key | Array String | Easy | |
| 1630. Arithmetic Subarrays | Array Hash Table Sorting | Medium | |
| 1631. Path With Minimum Effort | Depth-First Search Breadth-First Search Union Find Array Binary Search Matrix Heap (Priority Queue) | Medium | |
| 1632. Rank Transform of a Matrix | Union Find Graph Topological Sort Array Matrix Sorting | Hard | |
| 1634. Add Two Polynomials Represented as Linked Lists | Linked List Math Two Pointers | Medium | |
| 1636. Sort Array by Increasing Frequency | Array Hash Table Sorting | Easy | |
| 1637. Widest Vertical Area Between Two Points Containing No Points | Array Sorting | Easy | |
| 1638. Count Substrings That Differ by One Character | Hash Table String Dynamic Programming Enumeration | Medium | |
| 1639. Number of Ways to Form a Target String Given a Dictionary | Array String Dynamic Programming | Hard | |
| 1640. Check Array Formation Through Concatenation | Array Hash Table | Easy | |
| 1641. Count Sorted Vowel Strings | Math Dynamic Programming Combinatorics | Medium | |
| 1642. Furthest Building You Can Reach | Greedy Array Heap (Priority Queue) | Medium | |
| 1643. Kth Smallest Instructions | Array Math Dynamic Programming Combinatorics | Hard | |
| 1644. Lowest Common Ancestor of a Binary Tree II | Tree Depth-First Search Binary Tree | Medium | |
| 1646. Get Maximum in Generated Array | Array Simulation | Easy | |
| 1647. Minimum Deletions to Make Character Frequencies Unique | Greedy Hash Table String Sorting | Medium | |
| 1648. Sell Diminishing-Valued Colored Balls | Greedy Array Math Binary Search Sorting Heap (Priority Queue) | Medium | |
| 1649. Create Sorted Array through Instructions | Binary Indexed Tree Segment Tree Array Binary Search Divide and Conquer Ordered Set Merge Sort | Hard | |
| 1650. Lowest Common Ancestor of a Binary Tree III | Tree Hash Table Two Pointers Binary Tree | Medium | |
| 1652. Defuse the Bomb | Array Sliding Window | Easy | |
| 1653. Minimum Deletions to Make String Balanced | Stack String Dynamic Programming | Medium | |
| 1654. Minimum Jumps to Reach Home | Breadth-First Search Array Dynamic Programming | Medium | |
| 1655. Distribute Repeating Integers | Bit Manipulation Array Dynamic Programming Backtracking Bitmask | Hard | |
| 1656. Design an Ordered Stream | Design Array Hash Table Data Stream | Easy | |
| 1657. Determine if Two Strings Are Close | Hash Table String Counting Sorting | Medium | |
| 1658. Minimum Operations to Reduce X to Zero | Array Hash Table Binary Search Prefix Sum Sliding Window | Medium | |
| 1659. Maximize Grid Happiness | Bit Manipulation Memoization Dynamic Programming Bitmask | Hard | |
| 1660. Correct a Binary Tree | Tree Depth-First Search Breadth-First Search Hash Table Binary Tree | Medium | |
| 1662. Check If Two String Arrays are Equivalent | Array String | Easy | |
| 1663. Smallest String With A Given Numeric Value | Greedy String | Medium | |
| 1664. Ways to Make a Fair Array | Array Prefix Sum | Medium | |
| 1665. Minimum Initial Energy to Finish Tasks | Greedy Array Sorting | Hard | |
| 1666. Change the Root of a Binary Tree | Tree Depth-First Search Binary Tree | Medium | |
| 1668. Maximum Repeating Substring | String Dynamic Programming String Matching | Easy | |
| 1669. Merge In Between Linked Lists | Linked List | Medium | |
| 1670. Design Front Middle Back Queue | Design Queue Array Linked List Data Stream | Medium | |
| 1671. Minimum Number of Removals to Make Mountain Array | Greedy Array Binary Search Dynamic Programming | Hard | |
| 1672. Richest Customer Wealth | Array Matrix | Easy | |
| 1673. Find the Most Competitive Subsequence | Stack Greedy Array Monotonic Stack | Medium | |
| 1674. Minimum Moves to Make Array Complementary | Array Hash Table Prefix Sum | Medium | |
| 1675. Minimize Deviation in Array | Greedy Array Ordered Set Heap (Priority Queue) | Hard | |
| 1676. Lowest Common Ancestor of a Binary Tree IV | Tree Depth-First Search Hash Table Binary Tree | Medium | |
| 1678. Goal Parser Interpretation | String | Easy | |
| 1679. Max Number of K-Sum Pairs | Array Hash Table Two Pointers Sorting | Medium | |
| 1680. Concatenation of Consecutive Binary Numbers | Bit Manipulation Math Simulation | Medium | |
| 1681. Minimum Incompatibility | Bit Manipulation Array Dynamic Programming Bitmask | Hard | |
| 1682. Longest Palindromic Subsequence II | String Dynamic Programming | Medium | |
| 1684. Count the Number of Consistent Strings | Bit Manipulation Array Hash Table String Counting | Easy | |
| 1685. Sum of Absolute Differences in a Sorted Array | Array Math Prefix Sum | Medium | |
| 1686. Stone Game VI | Greedy Array Math Game Theory Sorting Heap (Priority Queue) | Medium | |
| 1687. Delivering Boxes from Storage to Ports | Segment Tree Queue Array Dynamic Programming Prefix Sum Monotonic Queue Heap (Priority Queue) | Hard | |
| 1688. Count of Matches in Tournament | Math Simulation | Easy | |
| 1689. Partitioning Into Minimum Number Of Deci-Binary Numbers | Greedy String | Medium | |
| 1690. Stone Game VII | Array Math Dynamic Programming Game Theory | Medium | |
| 1691. Maximum Height by Stacking Cuboids | Array Dynamic Programming Sorting | Hard | |
| 1692. Count Ways to Distribute Candies | Dynamic Programming | Hard | |
| 1694. Reformat Phone Number | String | Easy | |
| 1695. Maximum Erasure Value | Array Hash Table Sliding Window | Medium | |
| 1696. Jump Game VI | Queue Array Dynamic Programming Monotonic Queue Heap (Priority Queue) | Medium | |
| 1697. Checking Existence of Edge Length Limited Paths | Union Find Graph Array Two Pointers Sorting | Hard | |
| 1698. Number of Distinct Substrings in a String | Trie String Suffix Array Hash Function Rolling Hash | Medium | |
| 1700. Number of Students Unable to Eat Lunch | Stack Queue Array Simulation | Easy | |
| 1701. Average Waiting Time | Array Simulation | Medium | |
| 1702. Maximum Binary String After Change | Greedy String | Medium | |
| 1703. Minimum Adjacent Swaps for K Consecutive Ones | Greedy Array Prefix Sum Sliding Window | Hard | |
| 1704. Determine if String Halves Are Alike | String Counting | Easy | |
| 1705. Maximum Number of Eaten Apples | Greedy Array Heap (Priority Queue) | Medium | |
| 1706. Where Will the Ball Fall | Array Matrix Simulation | Medium | |
| 1707. Maximum XOR With an Element From Array | Bit Manipulation Trie Array | Hard | |
| 1708. Largest Subarray Length K | Greedy Array | Easy | |
| 1709. Biggest Window Between Visits | Database | Medium | |
| 1710. Maximum Units on a Truck | Greedy Array Sorting | Easy | |
| 1711. Count Good Meals | Array Hash Table | Medium | |
| 1712. Ways to Split Array Into Three Subarrays | Array Two Pointers Binary Search Prefix Sum | Medium | |
| 1713. Minimum Operations to Make a Subsequence | Greedy Array Hash Table Binary Search | Hard | |
| 1714. Sum Of Special Evenly-Spaced Elements In Array | Array Dynamic Programming | Hard | |
| 1716. Calculate Money in Leetcode Bank | Math | Easy | |
| 1717. Maximum Score From Removing Substrings | Stack Greedy String | Medium | |
| 1718. Construct the Lexicographically Largest Valid Sequence | Array Backtracking | Medium | |
| 1719. Number Of Ways To Reconstruct A Tree | Tree Graph | Hard | |
| 1720. Decode XORed Array | Bit Manipulation Array | Easy | |
| 1721. Swapping Nodes in a Linked List | Linked List Two Pointers | Medium | |
| 1722. Minimize Hamming Distance After Swap Operations | Depth-First Search Union Find Array | Medium | |
| 1723. Find Minimum Time to Finish All Jobs | Bit Manipulation Array Dynamic Programming Backtracking Bitmask | Hard | |
| 1724. Checking Existence of Edge Length Limited Paths II | Union Find Graph Minimum Spanning Tree | Hard | |
| 1725. Number Of Rectangles That Can Form The Largest Square | Array | Easy | |
| 1726. Tuple with Same Product | Array Hash Table Counting | Medium | |
| 1727. Largest Submatrix With Rearrangements | Greedy Array Matrix Sorting | Medium | |
| 1728. Cat and Mouse II | Graph Topological Sort Memoization Array Math Dynamic Programming Game Theory Matrix | Hard | |
| 1730. Shortest Path to Get Food | Breadth-First Search Array Matrix | Medium | |
| 1732. Find the Highest Altitude | Array Prefix Sum | Easy | |
| 1733. Minimum Number of People to Teach | Greedy Array Hash Table | Medium | |
| 1734. Decode XORed Permutation | Bit Manipulation Array | Medium | |
| 1735. Count Ways to Make Array With Product | Array Math Dynamic Programming Combinatorics Number Theory | Hard | |
| 1736. Latest Time by Replacing Hidden Digits | Greedy String | Easy | |
| 1737. Change Minimum Characters to Satisfy One of Three Conditions | Hash Table String Counting Prefix Sum | Medium | |
| 1738. Find Kth Largest XOR Coordinate Value | Bit Manipulation Array Divide and Conquer Matrix Prefix Sum Quickselect Sorting Heap (Priority Queue) | Medium | |
| 1739. Building Boxes | Greedy Math Binary Search | Hard | |
| 1740. Find Distance in a Binary Tree | Tree Depth-First Search Breadth-First Search Hash Table Binary Tree | Medium | |
| 1742. Maximum Number of Balls in a Box | Hash Table Math Counting | Easy | |
| 1743. Restore the Array From Adjacent Pairs | Depth-First Search Array Hash Table | Medium | |
| 1744. Can You Eat Your Favorite Candy on Your Favorite Day | Array Prefix Sum | Medium | |
| 1745. Palindrome Partitioning IV | String Dynamic Programming | Hard | |
| 1746. Maximum Subarray Sum After One Operation | Array Dynamic Programming | Medium | |
| 1748. Sum of Unique Elements | Array Hash Table Counting | Easy | |
| 1749. Maximum Absolute Sum of Any Subarray | Array Dynamic Programming | Medium | |
| 1750. Minimum Length of String After Deleting Similar Ends | Two Pointers String | Medium | |
| 1751. Maximum Number of Events That Can Be Attended II | Array Binary Search Dynamic Programming Sorting | Hard | |
| 1752. Check if Array Is Sorted and Rotated | Array | Easy | |
| 1753. Maximum Score From Removing Stones | Greedy Math Heap (Priority Queue) | Medium | |
| 1754. Largest Merge Of Two Strings | Greedy Two Pointers String | Medium | |
| 1755. Closest Subsequence Sum | Bit Manipulation Array Two Pointers Dynamic Programming Bitmask Sorting | Hard | |
| 1756. Design Most Recently Used Queue | Stack Design Binary Indexed Tree Array Hash Table Ordered Set | Medium | |
| 1758. Minimum Changes To Make Alternating Binary String | String | Easy | |
| 1759. Count Number of Homogenous Substrings | Math String | Medium | |
| 1760. Minimum Limit of Balls in a Bag | Array Binary Search | Medium | |
| 1761. Minimum Degree of a Connected Trio in a Graph | Graph Enumeration | Hard | |
| 1762. Buildings With an Ocean View | Stack Array Monotonic Stack | Medium | |
| 1763. Longest Nice Substring | Bit Manipulation Hash Table String Divide and Conquer Sliding Window | Easy | |
| 1764. Form Array by Concatenating Subarrays of Another Array | Greedy Array Two Pointers String Matching | Medium | |
| 1765. Map of Highest Peak | Breadth-First Search Array Matrix | Medium | |
| 1766. Tree of Coprimes | Tree Depth-First Search Array Math Number Theory | Hard | |
| 1768. Merge Strings Alternately | Two Pointers String | Easy | |
| 1769. Minimum Number of Operations to Move All Balls to Each Box | Array String Prefix Sum | Medium | |
| 1770. Maximum Score from Performing Multiplication Operations | Array Dynamic Programming | Hard | |
| 1771. Maximize Palindrome Length From Subsequences | String Dynamic Programming | Hard | |
| 1772. Sort Features by Popularity | Array Hash Table String Sorting | Medium | |
| 1773. Count Items Matching a Rule | Array String | Easy | |
| 1774. Closest Dessert Cost | Array Dynamic Programming Backtracking | Medium | |
| 1775. Equal Sum Arrays With Minimum Number of Operations | Greedy Array Hash Table Counting | Medium | |
| 1776. Car Fleet II | Stack Array Math Monotonic Stack Heap (Priority Queue) | Hard | |
| 1778. Shortest Path in a Hidden Grid | Depth-First Search Breadth-First Search Array Interactive Matrix | Medium | |
| 1779. Find Nearest Point That Has the Same X or Y Coordinate | Array | Easy | |
| 1780. Check if Number is a Sum of Powers of Three | Math | Medium | |
| 1781. Sum of Beauty of All Substrings | Hash Table String Counting | Medium | |
| 1782. Count Pairs Of Nodes | Graph Array Hash Table Two Pointers Binary Search Counting Sorting | Hard | |
| 1784. Check if Binary String Has at Most One Segment of Ones | String | Easy | |
| 1785. Minimum Elements to Add to Form a Given Sum | Greedy Array | Medium | |
| 1786. Number of Restricted Paths From First to Last Node | Graph Topological Sort Dynamic Programming Shortest Path Heap (Priority Queue) | Medium | |
| 1787. Make the XOR of All Segments Equal to Zero | Bit Manipulation Array Dynamic Programming | Hard | |
| 1788. Maximize the Beauty of the Garden | Greedy Array Hash Table Prefix Sum | Hard | |
| 1790. Check if One String Swap Can Make Strings Equal | Hash Table String Counting | Easy | |
| 1791. Find Center of Star Graph | Graph | Easy | |
| 1792. Maximum Average Pass Ratio | Greedy Array Heap (Priority Queue) | Medium | |
| 1793. Maximum Score of a Good Subarray | Stack Array Two Pointers Binary Search Monotonic Stack | Hard | |
| 1794. Count Pairs of Equal Substrings With Minimum Difference | Greedy Hash Table String | Medium | |
| 1796. Second Largest Digit in a String | Hash Table String | Easy | |
| 1797. Design Authentication Manager | Design Hash Table Linked List Doubly-Linked List | Medium | |
| 1798. Maximum Number of Consecutive Values You Can Make | Greedy Array Sorting | Medium | |
| 1799. Maximize Score After N Operations | Bit Manipulation Array Math Dynamic Programming Backtracking Bitmask Number Theory | Hard | |
| 1800. Maximum Ascending Subarray Sum | Array | Easy | |
| 1801. Number of Orders in the Backlog | Array Simulation Heap (Priority Queue) | Medium | |
| 1802. Maximum Value at a Given Index in a Bounded Array | Greedy Math Binary Search | Medium | |
| 1803. Count Pairs With XOR in a Range | Bit Manipulation Trie Array | Hard | |
| 1804. Implement Trie II (Prefix Tree) | Design Trie Hash Table String | Medium | |
| 1805. Number of Different Integers in a String | Hash Table String | Easy | |
| 1806. Minimum Number of Operations to Reinitialize a Permutation | Array Math Simulation | Medium | |
| 1807. Evaluate the Bracket Pairs of a String | Array Hash Table String | Medium | |
| 1808. Maximize Number of Nice Divisors | Recursion Math Number Theory | Hard | |
| 1810. Minimum Path Cost in a Hidden Grid | Depth-First Search Breadth-First Search Graph Array Interactive Matrix Shortest Path Heap (Priority Queue) | Medium | |
| 1811. Find Interview Candidates | Database | Medium | |
| 1812. Determine Color of a Chessboard Square | Math String | Easy | |
| 1813. Sentence Similarity III | Array Two Pointers String | Medium | |
| 1814. Count Nice Pairs in an Array | Array Hash Table Math Counting | Medium | |
| 1815. Maximum Number of Groups Getting Fresh Donuts | Bit Manipulation Memoization Array Dynamic Programming Bitmask | Hard | |
| 1816. Truncate Sentence | Array String | Easy | |
| 1817. Finding the Users Active Minutes | Array Hash Table | Medium | |
| 1818. Minimum Absolute Sum Difference | Array Binary Search Ordered Set Sorting | Medium | |
| 1819. Number of Different Subsequences GCDs | Array Math Counting Number Theory | Hard | |
| 1820. Maximum Number of Accepted Invitations | Depth-First Search Graph Array Matrix | Medium | |
| 1821. Find Customers With Positive Revenue this Year | Database | Easy | |
| 1822. Sign of the Product of an Array | Array Math | Easy | |
| 1823. Find the Winner of the Circular Game | Recursion Queue Array Math Simulation | Medium | |
| 1824. Minimum Sideway Jumps | Greedy Array Dynamic Programming | Medium | |
| 1825. Finding MK Average | Design Queue Data Stream Ordered Set Heap (Priority Queue) | Hard | |
| 1826. Faulty Sensor | Array Two Pointers | Easy | |
| 1827. Minimum Operations to Make the Array Increasing | Greedy Array | Easy | |
| 1828. Queries on Number of Points Inside a Circle | Geometry Array Math | Medium | |
| 1829. Maximum XOR for Each Query | Bit Manipulation Array Prefix Sum | Medium | |
| 1830. Minimum Number of Operations to Make String Sorted | Math String Combinatorics | Hard | |
| 1831. Maximum Transaction Each Day | Database | Medium | |
| 1832. Check if the Sentence Is Pangram | Hash Table String | Easy | |
| 1833. Maximum Ice Cream Bars | Greedy Array Counting Sort Sorting | Medium | |
| 1834. Single-Threaded CPU | Array Sorting Heap (Priority Queue) | Medium | |
| 1835. Find XOR Sum of All Pairs Bitwise AND | Bit Manipulation Array Math | Hard | |
| 1836. Remove Duplicates From an Unsorted Linked List | Hash Table Linked List | Medium | |
| 1837. Sum of Digits in Base K | Math | Easy | |
| 1838. Frequency of the Most Frequent Element | Greedy Array Binary Search Prefix Sum Sorting Sliding Window | Medium | |
| 1839. Longest Substring Of All Vowels in Order | String Sliding Window | Medium | |
| 1840. Maximum Building Height | Array Math Sorting | Hard | |
| 1841. League Statistics | Database | Medium | |
| 1842. Next Palindrome Using Same Digits | Two Pointers String | Hard | |
| 1844. Replace All Digits with Characters | String | Easy | |
| 1845. Seat Reservation Manager | Design Heap (Priority Queue) | Medium | |
| 1846. Maximum Element After Decreasing and Rearranging | Greedy Array Sorting | Medium | |
| 1847. Closest Room | Array Binary Search Ordered Set Sorting | Hard | |
| 1848. Minimum Distance to the Target Element | Array | Easy | |
| 1849. Splitting a String Into Descending Consecutive Values | String Backtracking Enumeration | Medium | |
| 1850. Minimum Adjacent Swaps to Reach the Kth Smallest Number | Greedy Two Pointers String | Medium | |
| 1851. Minimum Interval to Include Each Query | Array Binary Search Sorting Line Sweep Heap (Priority Queue) | Hard | |
| 1852. Distinct Numbers in Each Subarray | Array Hash Table Sliding Window | Medium | |
| 1853. Convert Date Format | Database | Easy | |
| 1854. Maximum Population Year | Array Counting Prefix Sum | Easy | |
| 1855. Maximum Distance Between a Pair of Values | Array Two Pointers Binary Search | Medium | |
| 1856. Maximum Subarray Min-Product | Stack Array Prefix Sum Monotonic Stack | Medium | |
| 1857. Largest Color Value in a Directed Graph | Graph Topological Sort Memoization Hash Table Dynamic Programming Counting | Hard | |
| 1858. Longest Word With All Prefixes | Depth-First Search Trie Array String | Medium | |
| 1859. Sorting the Sentence | String Sorting | Easy | |
| 1860. Incremental Memory Leak | Math Simulation | Medium | |
| 1861. Rotating the Box | Array Two Pointers Matrix | Medium | |
| 1862. Sum of Floored Pairs | Array Math Binary Search Prefix Sum | Hard | |
| 1863. Sum of All Subset XOR Totals | Bit Manipulation Array Math Backtracking Combinatorics Enumeration | Easy | |
| 1864. Minimum Number of Swaps to Make the Binary String Alternating | Greedy String | Medium | |
| 1865. Finding Pairs With a Certain Sum | Design Array Hash Table | Medium | |
| 1866. Number of Ways to Rearrange Sticks With K Sticks Visible | Math Dynamic Programming Combinatorics | Hard | |
| 1868. Product of Two Run-Length Encoded Arrays | Array Two Pointers | Medium | |
| 1869. Longer Contiguous Segments of Ones than Zeros | String | Easy | |
| 1870. Minimum Speed to Arrive on Time | Array Binary Search | Medium | |
| 1871. Jump Game VII | String Dynamic Programming Prefix Sum Sliding Window | Medium | |
| 1872. Stone Game VIII | Array Math Dynamic Programming Game Theory Prefix Sum | Hard | |
| 1874. Minimize Product Sum of Two Arrays | Greedy Array Sorting | Medium | |
| 1876. Substrings of Size Three with Distinct Characters | Hash Table String Counting Sliding Window | Easy | |
| 1877. Minimize Maximum Pair Sum in Array | Greedy Array Two Pointers Sorting | Medium | |
| 1878. Get Biggest Three Rhombus Sums in a Grid | Array Math Matrix Prefix Sum Sorting Heap (Priority Queue) | Medium | |
| 1879. Minimum XOR Sum of Two Arrays | Bit Manipulation Array Dynamic Programming Bitmask | Hard | |
| 1880. Check if Word Equals Summation of Two Words | String | Easy | |
| 1881. Maximum Value after Insertion | Greedy String | Medium | |
| 1882. Process Tasks Using Servers | Array Heap (Priority Queue) | Medium | |
| 1883. Minimum Skips to Arrive at Meeting On Time | Array Dynamic Programming | Hard | |
| 1884. Egg Drop With 2 Eggs and N Floors | Math Dynamic Programming | Medium | |
| 1885. Count Pairs in Two Arrays | Array Two Pointers Binary Search Sorting | Medium | |
| 1886. Determine Whether Matrix Can Be Obtained By Rotation | Array Matrix | Easy | |
| 1887. Reduction Operations to Make the Array Elements Equal | Array Sorting | Medium | |
| 1888. Minimum Number of Flips to Make the Binary String Alternating | String Dynamic Programming Sliding Window | Medium | |
| 1889. Minimum Space Wasted From Packaging | Array Binary Search Prefix Sum Sorting | Hard | |
| 1891. Cutting Ribbons | Array Binary Search | Medium | |
| 1893. Check if All the Integers in a Range Are Covered | Array Hash Table Prefix Sum | Easy | |
| 1894. Find the Student that Will Replace the Chalk | Array Binary Search Prefix Sum Simulation | Medium | |
| 1895. Largest Magic Square | Array Matrix Prefix Sum | Medium | |
| 1896. Minimum Cost to Change the Final Value of Expression | Stack Math String Dynamic Programming | Hard | |
| 1897. Redistribute Characters to Make All Strings Equal | Hash Table String Counting | Easy | |
| 1898. Maximum Number of Removable Characters | Array Two Pointers String Binary Search | Medium | |
| 1899. Merge Triplets to Form Target Triplet | Greedy Array | Medium | |
| 1900. The Earliest and Latest Rounds Where Players Compete | Memoization Dynamic Programming | Hard | |
| 1901. Find a Peak Element II | Array Binary Search Matrix | Medium | |
| 1902. Depth of BST Given Insertion Order | Tree Binary Search Tree Array Binary Tree Ordered Set | Medium | |
| 1903. Largest Odd Number in String | Greedy Math String | Easy | |
| 1904. The Number of Full Rounds You Have Played | Math String | Medium | |
| 1905. Count Sub Islands | Depth-First Search Breadth-First Search Union Find Array Matrix | Medium | |
| 1906. Minimum Absolute Difference Queries | Array Hash Table | Medium | |
| 1908. Game of Nim | Bit Manipulation Brainteaser Array Math Dynamic Programming Game Theory | Medium | |
| 1909. Remove One Element to Make the Array Strictly Increasing | Array | Easy | |
| 1910. Remove All Occurrences of a Substring | Stack String Simulation | Medium | |
| 1911. Maximum Alternating Subsequence Sum | Array Dynamic Programming | Medium | |
| 1912. Design Movie Rental System | Design Array Hash Table Ordered Set Heap (Priority Queue) | Hard | |
| 1913. Maximum Product Difference Between Two Pairs | Array Sorting | Easy | |
| 1914. Cyclically Rotating a Grid | Array Matrix Simulation | Medium | |
| 1915. Number of Wonderful Substrings | Bit Manipulation Hash Table String Prefix Sum | Medium | |
| 1916. Count Ways to Build Rooms in an Ant Colony | Tree Graph Topological Sort Math Dynamic Programming Combinatorics | Hard | |
| 1918. Kth Smallest Subarray Sum | Array Binary Search Sliding Window | Medium | |
| 1920. Build Array from Permutation | Array Simulation | Easy | |
| 1921. Eliminate Maximum Number of Monsters | Greedy Array Sorting | Medium | |
| 1922. Count Good Numbers | Recursion Math | Medium | |
| 1923. Longest Common Subpath | Array Binary Search Suffix Array Hash Function Rolling Hash | Hard | |
| 1924. Erect the Fence II | Geometry Array Math | Hard | |
| 1925. Count Square Sum Triples | Math Enumeration | Easy | |
| 1926. Nearest Exit from Entrance in Maze | Breadth-First Search Array Matrix | Medium | |
| 1927. Sum Game | Greedy Math String Game Theory | Medium | |
| 1928. Minimum Cost to Reach Destination in Time | Graph Array Dynamic Programming | Hard | |
| 1929. Concatenation of Array | Array Simulation | Easy | |
| 1930. Unique Length-3 Palindromic Subsequences | Bit Manipulation Hash Table String Prefix Sum | Medium | |
| 1931. Painting a Grid With Three Different Colors | Dynamic Programming | Hard | |
| 1932. Merge BSTs to Create Single BST | Tree Depth-First Search Hash Table Binary Search Binary Tree | Hard | |
| 1933. Check if String Is Decomposable Into Value-Equal Substrings | String | Easy | |
| 1935. Maximum Number of Words You Can Type | Hash Table String | Easy | |
| 1936. Add Minimum Number of Rungs | Greedy Array | Medium | |
| 1937. Maximum Number of Points with Cost | Array Dynamic Programming Matrix | Medium | |
| 1938. Maximum Genetic Difference Query | Bit Manipulation Depth-First Search Trie Array Hash Table | Hard | |
| 1940. Longest Common Subsequence Between Sorted Arrays | Array Hash Table Counting | Medium | |
| 1941. Check if All Characters Have Equal Number of Occurrences | Hash Table String Counting | Easy | |
| 1942. The Number of the Smallest Unoccupied Chair | Array Hash Table Heap (Priority Queue) | Medium | |
| 1943. Describe the Painting | Array Hash Table Prefix Sum Sorting | Medium | |
| 1944. Number of Visible People in a Queue | Stack Array Monotonic Stack | Hard | |
| 1945. Sum of Digits of String After Convert | String Simulation | Easy | |
| 1946. Largest Number After Mutating Substring | Greedy Array String | Medium | |
| 1947. Maximum Compatibility Score Sum | Bit Manipulation Array Dynamic Programming Backtracking Bitmask | Medium | |
| 1948. Delete Duplicate Folders in System | Trie Array Hash Table String Hash Function | Hard | |
| 1950. Maximum of Minimum Values in All Subarrays | Stack Array Monotonic Stack | Medium | |
| 1952. Three Divisors | Math Enumeration Number Theory | Easy | |
| 1953. Maximum Number of Weeks for Which You Can Work | Greedy Array | Medium | |
| 1954. Minimum Garden Perimeter to Collect Enough Apples | Math Binary Search | Medium | |
| 1955. Count Number of Special Subsequences | Array Dynamic Programming | Hard | |
| 1956. Minimum Time For K Virus Variants to Spread | Geometry Array Math Binary Search Enumeration | Hard | |
| 1957. Delete Characters to Make Fancy String | String | Easy | |
| 1958. Check if Move is Legal | Array Enumeration Matrix | Medium | |
| 1959. Minimum Total Space Wasted With K Resizing Operations | Array Dynamic Programming | Medium | |
| 1960. Maximum Product of the Length of Two Palindromic Substrings | String Hash Function Rolling Hash | Hard | |
| 1961. Check If String Is a Prefix of Array | Array Two Pointers String | Easy | |
| 1962. Remove Stones to Minimize the Total | Greedy Array Heap (Priority Queue) | Medium | |
| 1963. Minimum Number of Swaps to Make the String Balanced | Stack Greedy Two Pointers String | Medium | |
| 1964. Find the Longest Valid Obstacle Course at Each Position | Binary Indexed Tree Array Binary Search | Hard | |
| 1966. Binary Searchable Numbers in an Unsorted Array | Array Binary Search | Medium | |
| 1967. Number of Strings That Appear as Substrings in Word | Array String | Easy | |
| 1968. Array With Elements Not Equal to Average of Neighbors | Greedy Array Sorting | Medium | |
| 1969. Minimum Non-Zero Product of the Array Elements | Greedy Recursion Math | Medium | |
| 1970. Last Day Where You Can Still Cross | Depth-First Search Breadth-First Search Union Find Array Binary Search Matrix | Hard | |
| 1971. Find if Path Exists in Graph | Depth-First Search Breadth-First Search Union Find Graph | Easy | |
| 1973. Count Nodes Equal to Sum of Descendants | Tree Depth-First Search Binary Tree | Medium | |
| 1974. Minimum Time to Type Word Using Special Typewriter | Greedy String | Easy | |
| 1975. Maximum Matrix Sum | Greedy Array Matrix | Medium | |
| 1976. Number of Ways to Arrive at Destination | Graph Topological Sort Dynamic Programming Shortest Path | Medium | |
| 1977. Number of Ways to Separate Numbers | String Dynamic Programming Suffix Array | Hard | |
| 1979. Find Greatest Common Divisor of Array | Array Math Number Theory | Easy | |
| 1980. Find Unique Binary String | Array Hash Table String Backtracking | Medium | |
| 1981. Minimize the Difference Between Target and Chosen Elements | Array Dynamic Programming Matrix | Medium | |
| 1982. Find Array Given Subset Sums | Array Divide and Conquer | Hard | |
| 1983. Widest Pair of Indices With Equal Range Sum | Array Hash Table Prefix Sum | Medium | |
| 1984. Minimum Difference Between Highest and Lowest of K Scores | Array Sorting Sliding Window | Easy | |
| 1985. Find the Kth Largest Integer in the Array | Array String Divide and Conquer Quickselect Sorting Heap (Priority Queue) | Medium | |
| 1986. Minimum Number of Work Sessions to Finish the Tasks | Bit Manipulation Array Dynamic Programming Backtracking Bitmask | Medium | |
| 1987. Number of Unique Good Subsequences | String Dynamic Programming | Hard | |
| 1989. Maximum Number of People That Can Be Caught in Tag | Greedy Array | Medium | |
| 1991. Find the Middle Index in Array | Array Prefix Sum | Easy | |
| 1992. Find All Groups of Farmland | Depth-First Search Breadth-First Search Array Matrix | Medium | |
| 1993. Operations on Tree | Tree Depth-First Search Breadth-First Search Design Array Hash Table | Medium | |
| 1994. The Number of Good Subsets | Bit Manipulation Array Hash Table Math Dynamic Programming Bitmask Counting Number Theory | Hard | |
| 1995. Count Special Quadruplets | Array Hash Table Enumeration | Easy | |
| 1996. The Number of Weak Characters in the Game | Stack Greedy Array Sorting Monotonic Stack | Medium | |
| 1997. First Day Where You Have Been in All the Rooms | Array Dynamic Programming | Medium | |
| 1998. GCD Sort of an Array | Union Find Array Math Number Theory Sorting | Hard | |
| 1999. Smallest Greater Multiple Made of Two Digits | Math Enumeration | Medium | |
| 2000. Reverse Prefix of Word | Stack Two Pointers String | Easy | |
| 2001. Number of Pairs of Interchangeable Rectangles | Array Hash Table Math Counting Number Theory | Medium | |
| 2002. Maximum Product of the Length of Two Palindromic Subsequences | Bit Manipulation String Dynamic Programming Backtracking Bitmask | Medium | |
| 2003. Smallest Missing Genetic Value in Each Subtree | Tree Depth-First Search Union Find Dynamic Programming | Hard | |
| 2005. Subtree Removal Game with Fibonacci Tree | Tree Math Dynamic Programming Binary Tree Game Theory | Hard | |
| 2006. Count Number of Pairs With Absolute Difference K | Array Hash Table Counting | Easy | |
| 2007. Find Original Array From Doubled Array | Greedy Array Hash Table Sorting | Medium | |
| 2008. Maximum Earnings From Taxi | Array Hash Table Binary Search Dynamic Programming Sorting | Medium | |
| 2009. Minimum Number of Operations to Make Array Continuous | Array Hash Table Binary Search Sliding Window | Hard | |
| 2011. Final Value of Variable After Performing Operations | Array String Simulation | Easy | |
| 2012. Sum of Beauty in the Array | Array | Medium | |
| 2013. Detect Squares | Design Array Hash Table Counting | Medium | |
| 2014. Longest Subsequence Repeated k Times | Greedy String Backtracking Counting Enumeration | Hard | |
| 2015. Average Height of Buildings in Each Segment | Greedy Array Sorting Heap (Priority Queue) | Medium | |
| 2016. Maximum Difference Between Increasing Elements | Array | Easy | |
| 2017. Grid Game | Array Matrix Prefix Sum | Medium | |
| 2018. Check if Word Can Be Placed In Crossword | Array Enumeration Matrix | Medium | |
| 2019. The Score of Students Solving Math Expression | Stack Memoization Array Hash Table Math String Dynamic Programming | Hard | |
| 2021. Brightest Position on Street | Array Ordered Set Prefix Sum Sorting | Medium | |
| 2022. Convert 1D Array Into 2D Array | Array Matrix Simulation | Easy | |
| 2023. Number of Pairs of Strings With Concatenation Equal to Target | Array Hash Table String Counting | Medium | |
| 2024. Maximize the Confusion of an Exam | String Binary Search Prefix Sum Sliding Window | Medium | |
| 2025. Maximum Number of Ways to Partition an Array | Array Hash Table Counting Enumeration Prefix Sum | Hard | |
| 2027. Minimum Moves to Convert String | Greedy String | Easy | |
| 2028. Find Missing Observations | Array Math Simulation | Medium | |
| 2029. Stone Game IX | Greedy Array Math Counting Game Theory | Medium | |
| 2030. Smallest K Length Subsequence With Occurrences of a Letter | Stack Greedy String Monotonic Stack | Hard | |
| 2031. Count Subarrays With More Ones Than Zeros | Binary Indexed Tree Segment Tree Array Binary Search Divide and Conquer Ordered Set Merge Sort | Medium | |
| 2032. Two Out of Three | Bit Manipulation Array Hash Table | Easy | |
| 2033. Minimum Operations to Make a Uni-Value Grid | Array Math Matrix Sorting | Medium | |
| 2034. Stock Price Fluctuation | Design Hash Table Data Stream Ordered Set Heap (Priority Queue) | Medium |