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
- 0014Longest Common PrefixEasy
- 0049Group AnagramsMed
- 0056Merge IntervalsMed
- 0126Word Ladder IIHard
- 0127Word LadderHard
- 0151Reverse Words in a StringMed
- 0194Reverse Linked ListEasy
- 0195Course ScheduleMed
- 0206The Skyline ProblemHard
- 0230Valid AnagramEasy
- 0334Top K Frequent ElementsMed
- 0367Insert Delete GetRandom O(1)Med
- 0368Insert Delete GetRandom O(1) - Duplicates allowedHard
- 0381Decode StringMed
- 0430String CompressionMed
- 0513Random Pick with WeightMed
- 0547Find the Closest PalindromeHard
- 0568Minimum Index Sum of Two ListsEasy
Showing 20 of 28