# LeetCode 211. Design Add and Search Words Data Structure

Description https://leetcode.com/problems/design-add-and-search-words-data-structure/ Design a data structure that supports adding new words and finding if a string matches any previously added…

# LeetCode 535. Encode and Decode TinyURL

Description https://leetcode.com/problems/encode-and-decode-tinyurl/ Note: This is a companion problem to the System Design problem: Design TinyURL. TinyURL is a URL shortening service where you…

# LeetCode 981. Time Based Key-Value Store

Description https://leetcode.com/problems/time-based-key-value-store/ Design a time-based key-value data structure that can store multiple values for the same key at different time…

# LeetCode 398. Random Pick Index

Description https://leetcode.com/problems/random-pick-index/ Given an integer array nums with possible duplicates, randomly output the index of a given target number. You can assume that the given…

# LeetCode 706. Design HashMap

Description https://leetcode.com/problems/design-hashmap/ Design a HashMap without using any built-in hash table libraries. Implement the MyHashMap class: MyHashMap() initializes the object with an empty…

# LeetCode 1656. Design an Ordered Stream

Description https://leetcode.com/problems/design-an-ordered-stream/ There is a stream of n (idKey, value) pairs arriving in an arbitrary order, where idKey is an integer between 1 and n and value is a string. No two pairs…

# LeetCode 359. Logger Rate Limiter

Description https://leetcode.com/problems/logger-rate-limiter/ Design a logger system that receives a stream of messages along with their timestamps. Each unique message should only be…

# LeetCode 208. Implement Trie (Prefix Tree)

Description https://leetcode.com/problems/implement-trie-prefix-tree/ Implement a trie with insert, search, and startsWith methods. Example: Trie trie = new Trie(); trie.insert(“apple”); trie.search(“apple”); // returns true trie.search(“app”); //…

# LeetCode 380. Insert Delete GetRandom O(1)

Description https://leetcode.com/problems/insert-delete-getrandom-o1/ Design a data structure that supports all following operations in average O(1) time. insert(val): Inserts an item val to the set…

# LeetCode 384. Shuffle an Array

Description https://leetcode.com/problems/shuffle-an-array/ Shuffle a set of numbers without duplicates. Example: // Init an array with set 1, 2, and 3.…