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 662 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0004Median of Two Sorted ArraysHard
- 0010Regular Expression MatchingHard
- 0023Merge k Sorted ListsHard
- 0025Reverse Nodes in k-GroupHard
- 0030Substring with Concatenation of All WordsHard
- 0032Longest Valid ParenthesesHard
- 0037Sudoku SolverHard
- 0041First Missing PositiveHard
- 0042Trapping Rain WaterHard
- 0044Wildcard MatchingHard
- 0051N-QueensHard
- 0052N-Queens IIHard
- 0060Permutation SequenceHard
- 0065Valid NumberHard
- 0068Text JustificationHard
- 0076Minimum Window SubstringHard
- 0084Largest Rectangle in HistogramHard
- 0085Maximal RectangleHard
- 0087Scramble StringHard
- 0115Distinct SubsequencesHard
Showing 20 of 662