Data Structures problems
Stacks, queues, trees, heaps, tries. The containers that make algorithms fast.
355 problems125 Easy159 Medium71 Hard
50 problems
Stack Push and Pop Simulation
ds-001
Balanced Brackets
ds-002
Postfix Expression Evaluation
ds-003
Min Stack with O(1) Minimum
ds-004
Queue Implemented with Two Stacks
ds-005
Circular Queue Simulation
ds-006
Deque Operations
ds-007
Reverse a Singly Linked List
ds-008
Middle Node of a Linked List
ds-009
Merge Two Sorted Lists
ds-010
Remove Duplicates from Sorted List
ds-011
Doubly Linked List Insert and Delete
ds-012
Linked List Cycle Detection
ds-013
djb2 String Hash
ds-014
Hash Set Operations
ds-015
String Set Deduplication
ds-016
First Non-Repeating Character
ds-017
Binary Heap Parent and Child Indices
ds-018
Heap Sift Up
ds-019
Heapify Build Min-Heap
ds-020
Heap Push and Pop
ds-021
Kth Largest Element via Heap
ds-022
Trie Insert, Search, and StartsWith
ds-023
Trie Collect Words with Prefix
ds-024
BST Insert and Preorder Traversal
ds-025
BST Minimum and Maximum
ds-026
BST Height
ds-027
Validate Binary Search Tree
ds-028
Iterative Inorder Traversal
ds-029
Level-Order Traversal
ds-030
Build an Adjacency List
ds-031
Hash Map with Separate Chaining
ds-032
Union-Find Find with Path Compression
ds-033
Union-Find Union by Rank
ds-034
Detect Cycle in Undirected Graph via DSU
ds-035
Segment Tree Range Sum
ds-036
Fenwick Tree Prefix Sum
ds-037
LRU Cache
ds-038
Median Finder with Two Heaps
ds-039
Next Greater Element with Monotonic Stack
ds-040
Rotate Array by Reversal
ds-041
Partition Array by Pivot
ds-042
Find Missing and Duplicate
ds-043
Majority Element (Boyer-Moore)
ds-044
Two-Sum Indices with Hash Set
ds-045
Intersection of Two Arrays
ds-046
Union of Sorted Arrays
ds-047
Interval Merging with Sorted Sweep
ds-048
Insert into Sorted Array
ds-049
Binary Search on Sorted List
ds-050
Showing 50 of 355 problems.