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
- 0003Longest Substring Without Repeating CharactersMed
- 0004Median of Two Sorted ArraysHard
- 0005Longest Palindromic SubstringMed
- 0006Zigzag ConversionMed
- 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
- 0020Valid ParenthesesEasy
- 0022Generate ParenthesesMed
- 0026Remove Duplicates from Sorted ArrayEasy
- 0028Find the Index of the First Occurrence in a StringEasy
- 0031Next PermutationMed
- 0032Longest Valid ParenthesesHard
Showing 20 of 100