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 28 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0001Two SumEasy
- 0003Longest Substring Without Repeating CharactersMed
- 0005Longest Palindromic SubstringMed
- 0033Search in Rotated Sorted ArrayMed
- 0034Find First and Last Position of Element in Sorted ArrayMed
- 0048Rotate ImageMed
- 0071Simplify PathMed
- 0074Search a 2D MatrixMed
- 0125Valid PalindromeEasy
- 0155Min StackMed
- 0188Number of IslandsMed
- 0193Isomorphic StringsEasy
- 0194Reverse Linked ListEasy
- 0379Is SubsequenceEasy
- 0381Decode StringMed
- 0406Battleships in a BoardMed
- 0435Find All Numbers Disappeared in an ArrayEasy
- 0543Subarray Sum Equals KMed
- 0795Keys and RoomsMed
- 0798Backspace String CompareEasy
Showing 20 of 28