Keyword to Algorithm

"Top k"

• Heap: K closest points

"How many ways.."

• DFS: Decode ways
• DP: Robot paths

"Substring"

• Sliding window: Longest substring without repeating characters

"Palindrome"

• two pointers: Valid Palindrome
• DFS: Palindrome Partitioning
• DP: Palindrome Partitioning II

"Tree"

• shortest, level-order
  • BFS: Binary Tree Level-Order Traversal
• else: DFS: Max Depth

"Parentheses"

• Stack: Valid Parentheses

"Subarray"

• Sliding window: Maximum subarray sum
• Prefix sum: Subarray sum
• Hashmap: Continuous subarray sum

Max subarray

• Greedy: Kadane's Algorithm

"X Sum"

• Two pointer: Two sum

"Max/longest sequence"

• Dynamic programming, DFS: Longest increasing subsequence
• mono deque: Sliding window maximum

"Minimum/Shortest"

• Dynamic programming, DFS: Minimal path sum
• BFS: Shortest path

"Partition/split ... array/string"

• DFS: Decode ways

"Subsequence"

• Dynamic programming, DFS: Longest increasing subsequence
• Sliding window: Longest increasing subsequence

"Matrix"

• BFS, DFS: Flood fill, Islands
• Dynamic programming: Maximal square

"Jump"

• Greedy/DP: Jump game

"Game"

• Dynamic programming: Divisor game, Stone game