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 25 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0001Two SumEasy
- 0003Longest Substring Without Repeating CharactersMed
- 0004Median of Two Sorted ArraysHard
- 0005Longest Palindromic SubstringMed
- 0012Integer to RomanMed
- 0020Valid ParenthesesEasy
- 0021Merge Two Sorted ListsEasy
- 0033Search in Rotated Sorted ArrayMed
- 0049Group AnagramsMed
- 0064Minimum Path SumMed
- 0088Merge Sorted ArrayEasy
- 0093Restore IP AddressesMed
- 0102Binary Tree Level Order TraversalMed
- 0139Word BreakMed
- 0146LRU CacheMed
- 0155Min StackMed
- 0212Basic CalculatorHard
- 0227Sliding Window MaximumHard
- 0367Insert Delete GetRandom O(1)Med
- 0430String CompressionMed
Showing 20 of 25