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 45 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0001Two SumEasy
- 0002Add Two NumbersMed
- 0003Longest Substring Without Repeating CharactersMed
- 0013Roman to IntegerEasy
- 0020Valid ParenthesesEasy
- 0028Find the Index of the First Occurrence in a StringEasy
- 0042Trapping Rain WaterHard
- 0045Jump Game IIMed
- 0049Group AnagramsMed
- 0056Merge IntervalsMed
- 0070Climbing StairsEasy
- 0073Set Matrix ZeroesMed
- 0088Merge Sorted ArrayEasy
- 0121Best Time to Buy and Sell StockEasy
- 0146LRU CacheMed
- 0186House RobberMed
- 0188Number of IslandsMed
- 0194Reverse Linked ListEasy
- 0287Longest Increasing SubsequenceMed
- 0303Remove Duplicate LettersMed
Showing 20 of 45