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 34 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0012Integer to RomanMed
- 0021Merge Two Sorted ListsEasy
- 0025Reverse Nodes in k-GroupHard
- 0033Search in Rotated Sorted ArrayMed
- 0074Search a 2D MatrixMed
- 0079Word SearchMed
- 0092Reverse Linked List IIMed
- 0093Restore IP AddressesMed
- 0098Validate Binary Search TreeMed
- 0104Maximum Depth of Binary TreeEasy
- 0113Path Sum IIMed
- 0121Best Time to Buy and Sell StockEasy
- 0124Binary Tree Maximum Path SumHard
- 0143Reorder ListMed
- 0146LRU CacheMed
- 0191Remove Linked List ElementsEasy
- 0196Implement Trie (Prefix Tree)Med
- 0198Course Schedule IIMed
- 0205Contains DuplicateEasy
- 0207Contains Duplicate IIEasy
Showing 20 of 34