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
- 00153SumMed
- 0017Letter Combinations of a Phone NumberMed
- 0020Valid ParenthesesEasy
- 0021Merge Two Sorted ListsEasy
- 0026Remove Duplicates from Sorted ArrayEasy
- 0041First Missing PositiveHard
- 0049Group AnagramsMed
- 0056Merge IntervalsMed
- 0061Rotate ListMed
- 0121Best Time to Buy and Sell StockEasy
- 0175Largest NumberMed
- 0188Number of IslandsMed
- 0194Reverse Linked ListEasy
- 0205Contains DuplicateEasy
- 0206The Skyline ProblemHard
- 0222Palindrome Linked ListEasy
- 0230Valid AnagramEasy
- 0447LFU CacheHard
- 0582Maximum Product of Three NumbersEasy
Showing 20 of 25