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 50 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0001Two SumEasy
- 0002Add Two NumbersMed
- 0004Median of Two Sorted ArraysHard
- 0005Longest Palindromic SubstringMed
- 0011Container With Most WaterMed
- 0012Integer to RomanMed
- 0013Roman to IntegerEasy
- 00153SumMed
- 0020Valid ParenthesesEasy
- 0021Merge Two Sorted ListsEasy
- 0038Count and SayMed
- 0042Trapping Rain WaterHard
- 0050Pow(x, n)Med
- 0053Maximum SubarrayMed
- 0056Merge IntervalsMed
- 0078SubsetsMed
- 0079Word SearchMed
- 0098Validate Binary Search TreeMed
- 0118Pascal's TriangleEasy
- 0124Binary Tree Maximum Path SumHard
Showing 20 of 50