Keyword to Algorithm

This is a mapping of keywords you'll see in coding problems to the algorithms that solve them. If you are not experienced with solving coding problem, it may not make much sense now but don't worry we will learn all these later.

Use this guide as a reference when you're trying to identify which algorithm might be appropriate for a particular problem. The keywords and phrases listed below often signal that a specific algorithm or data structure approach would be effective.

"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