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 46 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0001Two SumEasy
- 0003Longest Substring Without Repeating CharactersMed
- 0007Reverse IntegerMed
- 0008String to Integer (atoi)Med
- 0009Palindrome NumberEasy
- 0019Remove Nth Node From End of ListMed
- 0020Valid ParenthesesEasy
- 0024Swap Nodes in PairsMed
- 0025Reverse Nodes in k-GroupHard
- 0026Remove Duplicates from Sorted ArrayEasy
- 0042Trapping Rain WaterHard
- 0046PermutationsMed
- 0048Rotate ImageMed
- 0050Pow(x, n)Med
- 0053Maximum SubarrayMed
- 0056Merge IntervalsMed
- 0058Length of Last WordEasy
- 0070Climbing StairsEasy
- 0088Merge Sorted ArrayEasy
- 0104Maximum Depth of Binary TreeEasy
Showing 20 of 46