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 94 matching · 2723 totalSort: id ↑
No.ProblemDifficulty
- 0146LRU CacheMed
- 0155Min StackMed
- 0173Binary Search Tree IteratorMed
- 0196Implement Trie (Prefix Tree)Med
- 0199Design Add and Search Words Data StructureMed
- 0213Implement Stack using QueuesEasy
- 0220Implement Queue using StacksEasy
- 0271Peeking IteratorMed
- 0282Find Median from Data StreamHard
- 0284Serialize and Deserialize Binary TreeHard
- 0290Range Sum Query - ImmutableEasy
- 0291Range Sum Query 2D - ImmutableMed
- 0294Range Sum Query - MutableMed
- 0328Flatten Nested List IteratorMed
- 0339Data Stream as Disjoint IntervalsHard
- 0342Design TwitterMed
- 0367Insert Delete GetRandom O(1)Med
- 0368Insert Delete GetRandom O(1) - Duplicates allowedHard
- 0371Shuffle an ArrayMed
- 0419All O`one Data StructureHard
Showing 20 of 94