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
12 of 12 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0001Two SumEasy
- 0003Longest Substring Without Repeating CharactersMed
- 0020Valid ParenthesesEasy
- 0056Merge IntervalsMed
- 0121Best Time to Buy and Sell StockEasy
- 0194Reverse Linked ListEasy
- 0214Invert Binary TreeEasy
- 0270Move ZeroesEasy
- 0374First Unique Character in a StringEasy
- 0381Decode StringMed
- 0850Monotonic ArrayEasy
- 0931Squares of a Sorted ArrayEasy
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