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 82 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0001Two SumEasy
- 0003Longest Substring Without Repeating CharactersMed
- 0004Median of Two Sorted ArraysHard
- 0005Longest Palindromic SubstringMed
- 0012Integer to RomanMed
- 0017Letter Combinations of a Phone NumberMed
- 0020Valid ParenthesesEasy
- 0021Merge Two Sorted ListsEasy
- 0023Merge k Sorted ListsHard
- 0031Next PermutationMed
- 0033Search in Rotated Sorted ArrayMed
- 0034Find First and Last Position of Element in Sorted ArrayMed
- 0039Combination SumMed
- 0046PermutationsMed
- 0047Permutations IIMed
- 0050Pow(x, n)Med
- 0053Maximum SubarrayMed
- 0056Merge IntervalsMed
- 0057Insert IntervalMed
- 0061Rotate ListMed
Showing 20 of 82