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 68 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0001Two SumEasy
- 0003Longest Substring Without Repeating CharactersMed
- 0004Median of Two Sorted ArraysHard
- 0006Zigzag ConversionMed
- 00153SumMed
- 0020Valid ParenthesesEasy
- 0021Merge Two Sorted ListsEasy
- 0022Generate ParenthesesMed
- 0031Next PermutationMed
- 0032Longest Valid ParenthesesHard
- 0037Sudoku SolverHard
- 0042Trapping Rain WaterHard
- 0049Group AnagramsMed
- 0054Spiral MatrixMed
- 0066Plus OneEasy
- 0070Climbing StairsEasy
- 0085Maximal RectangleHard
- 0102Binary Tree Level Order TraversalMed
- 0103Binary Tree Zigzag Level Order TraversalMed
- 0121Best Time to Buy and Sell StockEasy
Showing 20 of 68