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 42 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0003Longest Substring Without Repeating CharactersMed
- 0005Longest Palindromic SubstringMed
- 0011Container With Most WaterMed
- 00153SumMed
- 0017Letter Combinations of a Phone NumberMed
- 0020Valid ParenthesesEasy
- 0025Reverse Nodes in k-GroupHard
- 0040Combination Sum IIMed
- 0041First Missing PositiveHard
- 0042Trapping Rain WaterHard
- 0049Group AnagramsMed
- 0053Maximum SubarrayMed
- 0056Merge IntervalsMed
- 0071Simplify PathMed
- 0105Construct Binary Tree from Preorder and Inorder TraversalMed
- 0121Best Time to Buy and Sell StockEasy
- 0146LRU CacheMed
- 0153Find Minimum in Rotated Sorted ArrayMed
- 0177Repeated DNA SequencesMed
- 0186House RobberMed
Showing 20 of 42