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 40 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0001Two SumEasy
- 0002Add Two NumbersMed
- 0003Longest Substring Without Repeating CharactersMed
- 0005Longest Palindromic SubstringMed
- 0007Reverse IntegerMed
- 0009Palindrome NumberEasy
- 0014Longest Common PrefixEasy
- 00153SumMed
- 0020Valid ParenthesesEasy
- 0021Merge Two Sorted ListsEasy
- 0033Search in Rotated Sorted ArrayMed
- 0041First Missing PositiveHard
- 0042Trapping Rain WaterHard
- 0049Group AnagramsMed
- 0050Pow(x, n)Med
- 0056Merge IntervalsMed
- 0088Merge Sorted ArrayEasy
- 0092Reverse Linked List IIMed
- 0121Best Time to Buy and Sell StockEasy
- 0125Valid PalindromeEasy
Showing 20 of 40