Leetcode Problem Solutions

Id	Title	Difficulty	Java	Tags	Company
1	Two Sum	Easy	Solution	Array, Hash-table	Adobe, Airbnb, Amazon, Apple, Bloomberg, Dropbox, Facebook, Linkedin, Microsoft, Uber, Yahoo
2	Add Two Numbers	Medium	Solution	Linked-list, Math	Adobe, Airbnb, Amazon, Bloomberg, Microsoft
3	Longest Substring Without Repeating Characters	Medium	Solution	Hash-table, Two-pointers, String, Sliding-window	Adobe, Amazon, Bloomberg, Yelp
4	Median of Two Sorted Arrays	Hard	Solution	Array, Binary-search, Divide-and-conquer	Adobe, Apple, Dropbox, Google, Microsoft, Yahoo, Zenefits
5	Longest Palindromic Substring	Medium	Solution	String, Dynamic-programming	Amazon, Bloomberg, Microsoft, Google, TikTok, Cisco, Infosys, Facebook
11	Container With Most Water	Medium	Solution	Array, Two-pointers	Bloomberg
15	3Sum	Medium	Solution	Array, Two-pointers	Adobe, Amazon, Bloomberg, Facebook, Microsoft
17	Letter Combinations of a Phone Number	Medium	Solution	String, Backtracking	Amazon, Apple, Dropbox, Facebook, Google, Uber, Microsoft, Bloomberg, DE Shaw, Adobe, Intuit
19	Remove Nth Node From End of List	Medium	Solution	Linked-list, Two-pointers	Unknown
20	Valid Parentheses	Easy	Solution	String, Stack	Airbnb, Amazon, Bloomberg, Facebook, Google, Microsoft, Twitter, Zenefits
21	Merge Two Sorted Lists	Easy	Solution	Linked-list	Amazon, Apple, Linkedin, Microsoft
22	Generate Parentheses	Medium	Solution	String, Backtracking	Google, Uber, Zenefits
23	Merge k Sorted Lists	Hard	Solution	Linked-list, Divide-and-conquer, Heap	Airbnb, Amazon, Facebook, Google, Linkedin, Microsoft, Twitter, Uber
25	Reverse Nodes in k-Group	Hard	Solution	Linked-list	Facebook, Microsoft
33	Search in Rotated Sorted Array	Medium	Solution	Array, Binary-search	Bloomberg, Facebook, Linkedin, Microsoft, Uber
36	Valid Sudoku	Medium	Solution	Hash-table	Apple, Snapchat, Uber
39	Combination Sum	Medium	Solution	Array, Backtracking	Snapchat, Uber
40	Combination Sum II	Medium	Solution	Array, Backtracking	Snapchat
42	Trapping Rain Water	Hard	Solution	Array, Two-pointers, Stack	Amazon, Apple, Bloomberg, Google, Twitter, Zenefits
46	Permutations	Medium	Solution	Backtracking	Linkedin, Microsoft
51	N-Queens	Hard	Solution	Backtracking	Amazon, Adobe, Bloomberg, Google, Microsoft, Goldman Sachs, Facebook
70	Climbing Stairs	Easy	Solution	Dynamic-programming	Adobe, Apple, Amazon, Yahoo, Nagarro, Google, Bloomberg
74	Search a 2D Matrix	Medium	Solution	Array, Binary-search	Unknown
76	Minimum Window Substring	Hard	Solution	Hash-table, Two-pointers, String, Sliding-window	Facebook, Linkedin, Snapchat, Uber
78	Subsets	Medium	Solution	Array, Backtracking, Bit-manipulation	Amazon, Bloomberg, Facebook, Uber
79	Word Search	Medium	Solution	Array, Backtracking	Bloomberg, Facebook, Microsoft, Uber, Amazon, Google, Indeed, Apple, Walmart
84	Largest Rectangle in Histogram	Hard	Solution	Array, Stack	Unknown
90	Subsets II	Medium	Solution	Array, Backtracking	Facebook
91	Decode Ways	Medium	Solution	String, Dynamic-programming	Facebook, Microsoft, Uber, TikTok, Amazon, Cisco
98	Validate Binary Search Tree	Medium	Solution	Tree, Depth-first-search	Amazon, Bloomberg, Facebook, Microsoft
100	Same Tree	Easy	Solution	Tree, Depth-first-search	Bloomberg
102	Binary Tree Level Order Traversal	Medium	Solution	Tree, Breadth-first-search	Amazon, Apple, Bloomberg, Facebook, Linkedin, Microsoft
104	Maximum Depth of Binary Tree	Easy	Solution	Tree, Depth-first-search	Apple, Linkedin, Uber, Yahoo
105	Construct Binary Tree from Preorder and Inorder Traversal	Medium	Solution	Array, Tree, Depth-first-search	Bloomberg
110	Balanced Binary Tree	Easy	Solution	Tree, Depth-first-search	Bloomberg
121	Best Time to Buy and Sell Stock	Easy	Solution	Array, Dynamic-programming	Amazon, Bloomberg, Facebook, Microsoft, Uber
124	Binary Tree Maximum Path Sum	Hard	Solution	Tree, Depth-first-search	Baidu, Microsoft
125	Valid Palindrome	Easy	Solution	Two-pointers, String	Facebook, Microsoft, Uber, Zenefits
128	Longest Consecutive Sequence	Medium	Solution	Array, Union-find	Facebook, Google
130	Surrounded Regions	Medium	Solution	Depth-first-search, Breadth-first-search, Union-find	Amazon, Google, Uber, Bloomberg, Goldman Sachs, Salesforce
131	Palindrome Partitioning	Medium	Solution	Backtracking	Bloomberg, Amazon, Adobe, Google, Apple, Uber, Microsoft, Facebook
133	Clone Graph	Medium	Solution	Depth-first-search, Breadth-first-search, Graph	Facebook, Google, Pocketgems, Uber, Pinterest
138	Copy List with Random Pointer	Medium	Solution	Hash-table, Linked-list	Amazon, Bloomberg, Microsoft, Uber
139	Word Break	Medium	Solution	Dynamic-programming	Amazon, Bloomberg, Facebook, Google, Pocketgems, Uber, Yahoo, Tesla
141	Linked List Cycle	Easy	Solution	Linked-list, Two-pointers	Amazon, Bloomberg, Microsoft, Yahoo
143	Reorder List	Medium	Solution	Linked-list	Unknown
146	LRU Cache	Medium	Solution	Design	Amazon, Bloomberg, Facebook, Google, Microsoft, Palantir, Snapchat, Twitter, Uber, Yahoo, Zenefits
150	Evaluate Reverse Polish Notation	Medium	Solution	Stack	Linkedin
152	Maximum Product Subarray	Medium	Solution	Array, Dynamic-programming	Linkedin, Amazon, Microsoft, Apple, Uber, Google
153	Find Minimum in Rotated Sorted Array	Medium	Solution	Array, Binary-search	Microsoft
155	Min Stack	Medium	Solution	Stack, Design	Amazon, Bloomberg, Google, Snapchat, Uber, Zenefits
167	Two Sum II - Input Array Is Sorted	Medium	Solution	Array, Two-pointers, Binary-search	Amazon
169	Majority Element	Easy	Solution	Array, Divide-and-conquer, Bit-manipulation	Adobe, Zenefits
198	House Robber	Medium	Solution	Dynamic-programming	Airbnb, Linkedin, Cisco, Amazon, Google, Apple, Infosys, Walmart Labs
199	Binary Tree Right Side View	Medium	Solution	Tree, Depth-first-search, Breadth-first-search	Amazon
200	Number of Islands	Medium	Solution	Depth-first-search, Breadth-first-search, Union-find	Amazon, Facebook, Google, Microsoft, Zenefits, Bloomberg, LinkedIn, Apple
206	Reverse Linked List	Easy	Solution	Linked-list	Adobe, Amazon, Apple, Bloomberg, Facebook, Microsoft, Snapchat, Twitter, Uber, Yahoo, Yelp, Zenefits
207	Course Schedule	Medium	Solution	Depth-first-search, Breadth-first-search, Graph, Topological-sort	Amazon, Microsoft, Google, Facebook, tikTok, Apple, Uber, Yelp, Zenefits
208	Implement Trie (Prefix Tree)	Medium	Solution	Design, Trie	Bloomberg, Facebook, Google, Microsoft, Twitter, Uber
210	Course Schedule II	Medium	Solution	Depth-first-search, Breadth-first-search, Graph, Topological-sort	Facebook, Zenefits, Amazon, Google, Microsofit, Robinhood, VMware
211	Design Add and Search Words Data Structure	Medium	Solution	Backtracking, Design, Trie	Facebook
212	Word Search II	Hard	Solution	Backtracking, Trie	Airbnb, Google, Microsoft
213	House Robber II	Medium	Solution	Dynamic-programming	Microsoft, Google, Amazon, Adobe, Databricks, Bloomberg, TikTok
215	Kth Largest Element in an Array	Medium	Solution	Divide-and-conquer, Heap	Amazon, Apple, Bloomberg, Facebook, Microsoft, Pocketgems
217	Contains Duplicate	Easy	Solution	Array, Hash-table	Airbnb, Palantir, Yahoo
226	Invert Binary Tree	Easy	Solution	Tree	Unknown
230	Kth Smallest Element in a BST	Medium	Solution	Binary-search, Tree	Bloomberg, Google, Uber
235	Lowest Common Ancestor of a Binary Search Tree	Medium	Solution	Tree	Amazon, Facebook, Microsoft, Twitter
238	Product of Array Except Self	Medium	Solution	Array	Amazon, Apple, Facebook, Linkedin, Microsoft
239	Sliding Window Maximum	Hard	Solution	Heap, Sliding-window	Amazon, Google, Zenefits
242	Valid Anagram	Easy	Solution	Hash-table, Sort	Amazon, Uber, Yelp
261	Graph Valid Tree	Medium	Solution	Depth-first Search (DFS), Breadth-first Search (BFS), Union Find, Graph	Adobe, Amazon, Facebook, Google, LinkedIn, Pinterest, Salesforce, Zenefits
271	Encode and Decode Strings	Medium	Solution		Bloomberg, Google, Microsoft, Square, Twitter
286	Walls and Gates	Medium	Solution	BFS, DFS, Graphs	Amazon, Bloomberg, ByteDance, Facebook, Google, Microsoft, Uber
287	Find the Duplicate Number	Medium	Solution	Array, Two-pointers, Binary-search	Bloomberg
295	Find Median from Data Stream	Hard	Solution	Heap, Design	Google
297	Serialize and Deserialize Binary Tree	Hard	Solution	Tree, Design	Amazon, Bloomberg, Facebook, Google, Linkedin, Microsoft, Uber, Yahoo
300	Longest Increasing Subsequence	Medium	Solution	Binary-search, Dynamic-programming	Microsoft, Booking.com, Amazon, Bloomberg, Google
322	Coin Change	Medium	Solution	Dynamic-programming	Apple, Amazon, Yahoo, TikTok, Bloomberg, Microsoft
323	Number of Connected Components in an Undirected Graph	Medium	Solution	Depth-first Search (DFS), Breadth-first Search (BFS), Union Find, Graph	Amazon, Facebook, Google, LinkedIn, Microsoft, Twitter
347	Top K Frequent Elements	Medium	Solution	Hash-table, Heap	Pocketgems, Yelp
355	Design Twitter	Medium	Solution	Hash-table, Heap, Design	Amazon, Twitter
416	Partition Equal Subset Sum	Medium	Solution	Dynamic-programming	ebay, Amazon, Facebook, Microsoft, Apple, Google
417	Pacific Atlantic Water Flow	Medium	Solution	Depth-first-search , Breadth-first-search	Google, Uber, Amazon, Salesforce
424	Longest Repeating Character Replacement	Medium	Solution	Two-pointers, Sliding-window	Pocketgems
493	Reverse Pairs	Hard	Solution	Binary-search, Divide-and-conquer, Sort, Binary-indexed-tree, Segment-tree	Google
542	01 Matrix	Medium	Solution	Depth-first-search, Breadth-first-search	Google, Amazon, Uber
543	Diameter of Binary Tree	Easy	Solution	Tree	Facebook, Google
567	Permutation in String	Medium	Solution	Two-pointers, Sliding-window	Microsoft
572	Subtree of Another Tree	Easy	Solution	Tree	ebay, Facebook, Google
621	Task Scheduler	Medium	Solution	Array, Greedy, Priority-Queue	Facebook
647	Palindromic Substrings	Medium	Solution	String, Dynamic-programming	Facebook, Linkedin, Cisco, Goldman Sachs, Twitter
684	Redundant Connection	Medium	Solution	Tree, Union-find, Graph	Google, Microsoft, Amazon, Facebook, Apple
694	Number of Distinct Islands	Medium	Solution	Hash Table, Depth-first Search	Amazon, Apple, Bloomberg, Facebook, Google, Lyft, Microsoft, Uber
695	Max Area of Island	Medium	Solution	Array, Depth-first-search	Amazon, Facebook, Microsoft, DE Shaw, Bloomberg
703	Kth Largest Element in a Stream	Easy	Solution	Heap/Priority Queue	Unknown
704	Binary Search	Easy	Solution	Binary-search	Unknown
739	Daily Temperatures	Medium	Solution	Hash-table, Stack	Unknown
746	Min Cost Climbing Stairs	Easy	Solution	Dynamic-programming	Amazon, Apple, Bloomberg, Microsoft
853	Car Fleet	Medium	Solution	Two-pointers	Unknown
875	Koko Eating Bananas	Medium	Solution	Two-pointers, Binary-search	Unknown
973	K Closest Points to Origin	Medium	Solution	Array, Heaps/Priority Queue	Unknown
981	Time Based Key-Value Store	Medium	Solution	Binary Search, Greedy	Unknown
994	Rotting Oranges	Medium	Solution	Graph, Hash-table	Amazon, VMWare, Microsoft, LinkedIn
1046	Last Stone Weight	Easy	Solution	Heap/Priority Queue	Unknown
1448	Count Good Nodes in Binary Tree	Medium	Solution	Tree	Unknown
			Solution