B75

128. Longest Consecutive Sequence

Med.
Array
Hash Table
Union Find
1. Two Sum

Easy
Array
Hash Table
3. Longest Substring Without Repeating Characters

Med.
Hash Table
String
Sliding Window
5. Longest Palindromic Substring

Med.
Two Pointers
String
Dynamic Programming
133. Clone Graph

Med.
Hash Table
Depth-First Search
Breadth-First Search
Graph
261. Graph Valid Tree

Med.
Depth-First Search
Breadth-First Search
Union Find
Graph
647. Palindromic Substrings

Med.
Two Pointers
String
Dynamic Programming
11. Container With Most Water

Med.
Array
Two Pointers
Greedy
139. Word Break

Med.
Array
Hash Table
String
Dynamic Programming
2+
141. Linked List Cycle

Easy
Hash Table
Linked List
Two Pointers
268. Missing Number

Easy
Array
Hash Table
Math
Binary Search
2+
15. 3Sum

Med.
Array
Two Pointers
Sorting
143. Reorder List

Med.
Linked List
Two Pointers
Stack
Recursion
269. Alien Dictionary

Hard
Array
String
Depth-First Search
Breadth-First Search
2+
271. Encode and Decode Strings

Med.
Array
String
Design
19. Remove Nth Node From End of List

Med.
Linked List
Two Pointers
20. Valid Parentheses

Easy
String
Stack
21. Merge Two Sorted Lists

Easy
Linked List
Recursion
23. Merge k Sorted Lists

Hard
Linked List
Divide and Conquer
Heap (Priority Queue)
Merge Sort
152. Maximum Product Subarray

Med.
Array
Dynamic Programming
153. Find Minimum in Rotated Sorted Array

Med.
Array
Binary Search
33. Search in Rotated Sorted Array

Med.
Array
Binary Search
417. Pacific Atlantic Water Flow

Med.
Array
Depth-First Search
Breadth-First Search
Matrix
39. Combination Sum

Med.
Array
Backtracking
295. Find Median from Data Stream

Hard
Two Pointers
Design
Sorting
Heap (Priority Queue)
1+
424. Longest Repeating Character Replacement

Med.
Hash Table
String
Sliding Window
300. Longest Increasing Subsequence

Med.
Array
Binary Search
Dynamic Programming
48. Rotate Image

Med.
Array
Math
Matrix
49. Group Anagrams

Med.
Array
Hash Table
String
Sorting
435. Non-overlapping Intervals

Med.
Array
Dynamic Programming
Greedy
Sorting
53. Maximum Subarray

Med.
Array
Divide and Conquer
Dynamic Programming
54. Spiral Matrix

Med.
Array
Matrix
Simulation
55. Jump Game

Med.
Array
Dynamic Programming
Greedy
56. Merge Intervals

Med.
Array
Sorting
57. Insert Interval

Med.
Array
572. Subtree of Another Tree

Easy
Tree
Depth-First Search
String Matching
Binary Tree
1+
62. Unique Paths

Med.
Math
Dynamic Programming
Combinatorics
190. Reverse Bits

Easy
Divide and Conquer
Bit Manipulation
191. Number of 1 Bits

Easy
Divide and Conquer
Bit Manipulation
449. Serialize and Deserialize BST

Med.
String
Tree
Depth-First Search
Breadth-First Search
3+
322. Coin Change

Med.
Array
Dynamic Programming
Breadth-First Search
323. Number of Connected Components in an Undirected Graph

Med.
Depth-First Search
Breadth-First Search
Union Find
Graph
70. Climbing Stairs

Easy
Math
Dynamic Programming
Memoization
198. House Robber

Med.
Array
Dynamic Programming
200. Number of Islands

Med.
Array
Depth-First Search
Breadth-First Search
Union Find
1+
73. Set Matrix Zeroes

Med.
Array
Hash Table
Matrix
76. Minimum Window Substring

Hard
Hash Table
String
Sliding Window
206. Reverse Linked List

Easy
Linked List
Recursion
79. Word Search

Med.
Array
String
Backtracking
Matrix
207. Course Schedule

Med.
Depth-First Search
Breadth-First Search
Graph
Topological Sort
208. Implement Trie (Prefix Tree)

Med.
Hash Table
String
Design
Trie
338. Counting Bits

Easy
Dynamic Programming
Bit Manipulation
211. Design Add and Search Words Data Structure

Med.
String
Depth-First Search
Design
Trie
212. Word Search II

Hard
Array
String
Backtracking
Trie
1+
213. House Robber II

Med.
Array
Dynamic Programming
217. Contains Duplicate

Easy
Array
Hash Table
Sorting
91. Decode Ways

Med.
String
Dynamic Programming
347. Top K Frequent Elements

Med.
Array
Hash Table
Divide and Conquer
Sorting
4+
253. Meeting Rooms II

Med.
Array
Two Pointers
Greedy
Sorting
2+
98. Validate Binary Search Tree

Med.
Tree
Depth-First Search
Binary Search Tree
Binary Tree
226. Invert Binary Tree

Easy
Tree
Depth-First Search
Breadth-First Search
Binary Tree
100. Same Tree

Easy
Tree
Depth-First Search
Breadth-First Search
Binary Tree
1143. Longest Common Subsequence

Med.
String
Dynamic Programming
102. Binary Tree Level Order Traversal

Med.
Tree
Breadth-First Search
Binary Tree
230. Kth Smallest Element in a BST

Med.
Tree
Depth-First Search
Binary Search Tree
Binary Tree
104. Maximum Depth of Binary Tree

Easy
Tree
Depth-First Search
Breadth-First Search
Binary Tree
105. Construct Binary Tree from Preorder and Inorder Traversal

Med.
Array
Hash Table
Divide and Conquer
Tree
1+
235. Lowest Common Ancestor of a Binary Search Tree

Med.
Tree
Depth-First Search
Binary Search Tree
Binary Tree
236. Lowest Common Ancestor of a Binary Tree

Med.
Tree
Depth-First Search
Binary Tree
238. Product of Array Except Self

Med.
Array
Prefix Sum
242. Valid Anagram

Easy
Hash Table
String
Sorting
371. Sum of Two Integers

Med.
Math
Bit Manipulation
252. Meeting Rooms

Easy
Array
Sorting
121. Best Time to Buy and Sell Stock

Easy
Array
Dynamic Programming
124. Binary Tree Maximum Path Sum

Hard
Dynamic Programming
Tree
Depth-First Search
Binary Tree
125. Valid Palindrome

Easy
Two Pointers
String