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 100 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0001Two SumEasy
- 0002Add Two NumbersMed
- 0003Longest Substring Without Repeating CharactersMed
- 0004Median of Two Sorted ArraysHard
- 0005Longest Palindromic SubstringMed
- 0006Zigzag ConversionMed
- 0007Reverse IntegerMed
- 0008String to Integer (atoi)Med
- 0009Palindrome NumberEasy
- 0010Regular Expression MatchingHard
- 0011Container With Most WaterMed
- 0012Integer to RomanMed
- 0013Roman to IntegerEasy
- 0014Longest Common PrefixEasy
- 00153SumMed
- 00163Sum ClosestMed
- 0017Letter Combinations of a Phone NumberMed
- 00184SumMed
- 0019Remove Nth Node From End of ListMed
- 0020Valid ParenthesesEasy
Showing 20 of 100