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
17 of 17 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0004Median of Two Sorted ArraysHard
- 0020Valid ParenthesesEasy
- 0022Generate ParenthesesMed
- 0042Trapping Rain WaterHard
- 0052N-Queens IIHard
- 0109Convert Sorted List to Binary Search TreeMed
- 0125Valid PalindromeEasy
- 0146LRU CacheMed
- 0155Min StackMed
- 0168Excel Sheet Column TitleEasy
- 0169Majority ElementEasy
- 0188Number of IslandsMed
- 0194Reverse Linked ListEasy
- 0195Course ScheduleMed
- 0198Course Schedule IIMed
- 0217Majority Element IIMed
- 0227Sliding Window MaximumHard
All 17 matching problems loaded