Data Structure

Array:

1. Circular Array

Linked List:

1. Design Singly Linked List
2. Design Doubly Linked List
3. Design Skiplist

Stack / Queues:

1. Min Stack
2. Max Stack
3. Implement Queue using Stacks
4. Implement Stack using Queues
5. Design Circular Deque
6. Design Circular Queue
7. Moving Average from Data Stream
8. Design Bounded Blocking Queue
9. Design a Stack With Increment Operation

HashTable:

1. Design a Hash Table Hash Table
   1. Design HashSet
   2. Design HashMap
2. Unique Word Abbreviation
3. Two Sum III – Data structure design
4. Shortest Word Distance II
5. Insert Delete GetRandom O(1)
6. Insert Delete GetRandom O(1) – Duplicates allowed
7. Time Based Key-Value Store

Trees:

1. Binary Search Tree Iterator
2. Serialize and Deserialize BST
3. Serialize and Deserialize Binary Tree
4. Serialize and Deserialize N-ary Tree

Heap:

1. Find Median from Data Stream

Trie:

1. Implement Trie (Prefix Tree)
2. Add and Search Word – Data structure design
3. Prefix and Suffix Search
4. Search Suggestions System

Cache: 

1. LRU Cache
2. LFU Cache
3. Design In-Memory File System

File:

1. Design a File Sharing System
2. Design File System
3. Find Duplicate File in System
4. Design Log Storage System  
5. Design Underground System

Similar:

1. Flatten 2D Vector
2. Nested List Weight Sum
3. Flatten Nested List Iterator
4. Peeking Iterator
5. Zigzag Iterator
6. Design Compressed String Iterator
7. Iterator for Combination
8. Flatten a Dictionary

General Design:

1. Design Search Autocomplete System
2. Design Tic-Tac-Toe | Valid Tic-Tac-Toe State | Find Winner on a Tic Tac Toe Game
3. Design Log Storage System
4. Design Snake Game
5. Design Phone Directory
6. Design Twitter
7. Design Hit Counter
8. Logger Rate Limiter
9. Design Excel Sum Formula
10. Design A Leaderboard
11. Design Browser History
12. Dinner Plate Stacks
13. All O`one Data Structure