continually updating 😃.

• 1. Two Sum   lookup table;  hash table
• 4. Median of Two Sorted Arrays   binary search;  divide and conquer
• 11. Container With Most Water   double index;  array
• 26. Remove Duplicates from Sorted Array   double index;  array
• 27. Remove Element   double index;  array
• 48. Rotate Image
• 53. Maximum Subarray   dynamic programming
• 75. Sort Colors   sort;  array
• 80. Remove Duplicates from Sorted Array II   double index;  array
• 88. Merge Sorted Array   sort;  array
• 121. Best Time to Buy and Sell Stock   dynamic programming;  array
• 122. Best Time to Buy and Sell Stock II   greedy;  array
• 167. Two Sum II - Input array is sorted   double index;  binary search
• 179. Largest Number   sort
• 200. Number of Islands   dfs;  bfs
• 209. Minimum Size Subarray Sum   sliding window
• 215. Kth Largest Element in an Array   sort
• 217. Contains Duplicate   map
• 219. Contains Duplicate II   map
• 283. Move Zeroes(solution1)   sliding window
• 283. Move Zeroes(solution2)   sliding window
• 303. Range Sum Query - Immutable
• 347. Top K Frequent Elements   hash table;  heap
• 349. Intersection of Two Arrays   set
• 350. Intersection of Two Arrays II   hash table
• 447. Number of Boomerangs   hash table
• 454. 4Sum II   hash table
• 674. Longest Continuous Increasing Subsequence
• 713. Subarray Product Less Than K   sliding window  array
• 717. 1-bit and 2-bit Characters
• 747. Largest Number At Least Twice of Others

• 155. Min Stack
• 735. Asteroid Collision

• 3. Longest Substring Without Repeating Characters   sliding window;  hash table
• 14. Longest Common Prefix
• 17. Letter Combinations of a Phone Number   tree
• 20. Valid Parentheses   stack
• 28. Implement strStr()   double index
• 58. Length of Last Word
• 67. Add Binary   brute force
• 76. Minimum Window Substring    sliding window
• 125. Valid Palindrome   string;  double index
• 165. Compare Version Numbers
• 344. Reverse String   string;  double index
• 345. Reverse Vowels of a String   string;  double index
• 438. Find All Anagrams in a String   sliding window
• 557. Reverse Words in a String III

• 2. Add Two Numbers   recursion;  math
• 19. Remove Nth Node From End of List   two pointers
• 21. Merge Two Sorted Lists
• 23. Merge k Sorted Lists   heap
• 24. Swap Nodes in Pairs
• 25. Reverse Nodes in k-Group
• 61. Rotate List
• 82. Remove Duplicates from Sorted List II
• 83. Remove Duplicates from Sorted List
• 86. Partition List   two pointers
• 92. Reverse Linked List II
• 203. Remove Linked List Elements
• 206. Reverse Linked List
• 237. Delete Node in a Linked List
• 328. Odd Even Linked List

• 62. Unique Paths   array
• 63. Unique Paths 2   array
• 64. Minimum Path Sum   array
• 70. Climbing Stairs
• 120. Triangle   array
• 198. House Robber
• 300. Longest Increasing Subsequence
• 343. Integer Break   math
• 376. Wiggle Subsequence   greedy;  dynamic programming
• 416. Partition Equal Subset Sum  0-1 knapsack problem
• 435. Non-overlapping Intervals   greedy;  dynamic programming  0-1 knapsack problem

• 392. Is Subsequence
• 435. Non-overlapping Intervals   greedy;  dynamic programming
• 455. Assign Cookies

• 77. Combinations   combine
• 79. Word Search   array

• 94. Binary Tree Inorder Traversal   binary tree;   stack
• 100. Same Tree   binary tree;   dfs
• 101. Symmetric Tree   binary tree;   dfs;  bfs;
• 102. Binary Tree Level Order Traversal   binary tree;   dfs
• 104. Maximum Depth of Binary Tree   binary tree depth
• 107. Binary Tree Level Order Traversal II   binary tree;   bfs
• 111. Minimum Depth of Binary Tree   binary tree;   dfs
• 112. Path Sum   binary tree;   dfs
• 144. Binary Tree Preorder Traversal   binary tree;   pre-order traversal
• 208. Implement Trie (Prefix Tree)   trie
• 226. Invert Binary Tree   binary tree
• 211. Add and Search Word - Data structure design   trie
• 235. Lowest Common Ancestor of a Binary Search Tree   binary tree
• 257. Binary Tree Paths   binary tree
• 307. Range Sum Query - Mutable   segment tree
• 404. Sum of Left Leaves   binary tree
• 437. Path Sum III   binary tree
• 872. Leaf-Similar Trees   binary tree

• 33. Search in Rotated Sorted Array   array;  binary search
• 34. Find First and Last Position of Element in Sorted Array   array;  binary search
• 35. Search Insert Position   array;  binary search
• 69. Sqrt(x)   math;  binary search
• 153. Find Minimum in Rotated Sorted Array
• 704. Binary Search

• 7. Reverse Integer
• 9. Palindrome Number
• 13. Roman to Integer   string
• 66. Plus One   array
• 150. Evaluate Reverse Polish Notation   stack
• 258. Add Digits