Grind 75

1. Two Sum

Array Hash Table Easy

3. Longest Substring Without Repeating Characters

Hash Table String Sliding Window Medium

5. Longest Palindromic Substring

Two Pointers String Dynamic Programming Medium

383. Ransom Note

Hash Table String Counting Easy

8. String to Integer (atoi)

String Medium

11. Container With Most Water

Array Two Pointers Greedy Medium

139. Word Break

Array Hash Table String Dynamic Programming Trie Memoization Medium

141. Linked List Cycle

Hash Table Linked List Two Pointers Easy

876. Middle of the Linked List

Linked List Two Pointers Easy

15. 3Sum

Array Two Pointers Sorting Medium

994. Rotting Oranges

Array Breadth-First Search Matrix Medium

17. Letter Combinations of a Phone Number

Hash Table String Backtracking Medium

146. LRU Cache

Hash Table Linked List Design Doubly-Linked List Medium

20. Valid Parentheses

String Stack Easy

409. Longest Palindrome

Hash Table String Greedy Easy

322. Coin Change

Array Dynamic Programming Breadth-First Search Medium

125. Valid Palindrome

Two Pointers String Easy