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 46 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0001Two SumEasy
- 0002Add Two NumbersMed
- 0010Regular Expression MatchingHard
- 0020Valid ParenthesesEasy
- 0023Merge k Sorted ListsHard
- 0039Combination SumMed
- 0042Trapping Rain WaterHard
- 0056Merge IntervalsMed
- 0068Text JustificationHard
- 0076Minimum Window SubstringHard
- 0108Convert Sorted Array to Binary Search TreeEasy
- 0136Single NumberEasy
- 0160Intersection of Two Linked ListsEasy
- 0166Fraction to Recurring DecimalMed
- 0180Reverse BitsEasy
- 0186House RobberMed
- 0190Happy NumberEasy
- 0200Word Search IIHard
- 0205Contains DuplicateEasy
- 0207Contains Duplicate IIEasy
Showing 20 of 46