design

LRU Cache

Implement an efficient LRU Cache using hash table and doubly-linked list to achieve O(1) operations for get and put.

Min Stack

Design a stack with O(1) operations to push, pop, retrieve the top element, and get the minimum element in constant time…

Binary Search Tree Iterator

Implement an iterator for in-order traversal of a binary search tree (BST), maintaining traversal state with stack-based…

Implement Trie (Prefix Tree)

This problem requires designing a Trie (Prefix Tree) to efficiently store and query strings using hash table concepts fo…

Design Add and Search Words Data Structure

Build a WordDictionary supporting dynamic word addition and search with wildcard matching efficiently using Trie and DFS…

Implement Stack using Queues

This problem tests your ability to simulate a LIFO stack using two queues while preserving all standard stack operations…

Implement Queue using Stacks

Implement a queue using two stacks, focusing on stack-based state management to achieve FIFO behavior in a queue.

Peeking Iterator

Design an iterator with peek functionality, adding to the standard next and hasNext operations for efficient element acc…

Find Median from Data Stream

Implement a MedianFinder class that supports adding numbers and finding the median from a data stream.

Serialize and Deserialize Binary Tree

This problem asks to serialize and deserialize a binary tree, requiring an efficient approach to handle traversal and st…

Range Sum Query - Immutable

The Range Sum Query - Immutable problem involves implementing a data structure to handle range sum queries efficiently.

Range Sum Query 2D - Immutable

Design a 2D matrix class that efficiently handles sum queries with O(1) time complexity using a prefix sum approach.

Range Sum Query - Mutable

Implement a mutable range sum query using efficient design patterns to handle multiple updates and range sum queries.

Flatten Nested List Iterator

Implement an iterator to flatten a nested list of integers, accounting for potential nesting levels.

Data Stream as Disjoint Intervals

The problem involves designing a class to summarize a data stream of non-negative integers as disjoint intervals using b…

Design Twitter

Design Twitter requires implementing post, follow, unfollow, and news feed retrieval using linked-list pointer manipulat…

Insert Delete GetRandom O(1)

Implement a data structure supporting insert, delete, and getRandom in average O(1) using array plus hash mapping.

Insert Delete GetRandom O(1) - Duplicates allowed

This problem challenges you to design a data structure that supports insertion, removal, and random access with O(1) tim…

Shuffle an Array

Shuffle an Array requires designing a class to randomly permute an integer array while ensuring all permutations are equ…

All O`one Data Structure

Implement a data structure that tracks string counts and retrieves max or min keys efficiently in constant time.

Serialize and Deserialize BST

Design an algorithm to serialize and deserialize a binary search tree with efficient traversal and state tracking.

LFU Cache

Implement an LFU Cache using linked-list pointer manipulation with constant-time get and put operations for interview sc…

Encode and Decode TinyURL

Design a class that encodes and decodes URLs using a URL shortening approach based on hash tables and strings.

Design Circular Queue

Design a circular queue that allows efficient FIFO operations using linked-list pointer manipulation to optimize space u…