DSA
Master the patterns
Search the bank, then filter by difficulty, pattern, data structure, or algorithm. Each problem includes approaches, solutions, and walkthroughs.
Active·2,723
Easy·667
Medium·1,394
Hard·662
Patterns
Recognize the move
Filter the bank by pattern — each card links into the problem index.
Problem index
Browse problems
Search by title, then refine with facets. Sorted by problem ID.
Difficulty
Facets
20 of 31 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0001Two SumEasy
- 0003Longest Substring Without Repeating CharactersMed
- 0012Integer to RomanMed
- 00153SumMed
- 0023Merge k Sorted ListsHard
- 0056Merge IntervalsMed
- 0075Sort ColorsMed
- 0133Clone GraphMed
- 0138Copy List with Random PointerMed
- 0146LRU CacheMed
- 0171Excel Sheet Column NumberEasy
- 0188Number of IslandsMed
- 0196Implement Trie (Prefix Tree)Med
- 0199Design Add and Search Words Data StructureMed
- 0201House Robber IIMed
- 0226Product of Array Except SelfMed
- 0282Find Median from Data StreamHard
- 0334Top K Frequent ElementsMed
- 0367Insert Delete GetRandom O(1)Med
- 0489IPOHard
Showing 20 of 31