Introduction

Complete solutions to Leetcode problems, updated daily.

Solution List

Easy

#	Title	Tags
001	Two Sum	Array, Hash Table
007	Reverse Integer	Math
009	Palindrome Number	Math
013	Roman to Integer	Math, String
014	Longest Common Prefix	String
020	Valid Parentheses	String, Stack
021	Merge Two Sorted Lists	Linked List
028	Implement strStr()	Two Pointers, String
035	Search Insert Position	Array, Binary Search
053	Maximum Subarray	Array, Divide and Conquer, Dynamic Programming
070	Climbing Stairs	Dynamic Programming
083	Remove Duplicates from Sorted List	Linked List
136	Single Number	Hash Table, Bit Manipulation
141	Linked List Cycle	Linked List, Two Pointers
155	Min Stack	Stack, Design
175	Combine Two Tables	SQL
176	Second Highest Salary	SQL
181	Employees Earning More Than Their Managers	SQL
182	Duplicate Emails	SQL
183	Customers Who Never Order	SQL
189	Rotate Array	Array
196	Delete Duplicate Emails	SQL
197	Rising Temperature	SQL
198	House Robber	Dynamic Programming
203	Remove Linked List Elements	Linked List
231	Power of Two	Math, Bit Manipulation
234	Palindrome Linked List	Linked List, Two Pointers
235	Lowest Common Ancestor of a Binary Search Tree	Tree
237	Delete Node in a Linked List	Linked List
344	Reverse String	Two Pointers, String
581	Shortest Unsorted Continuous Subarray	Array
595	Big Countries	SQL
596	Classes More Than 5 Students	SQL
605	Can Place Flowers	Array
620	Not Boring Movies	SQL
627	Swap Salary	SQL
695	Max Area of Island	Array, Depth-first Search
703	Kth Largest Element in a Stream	Heap
707	Design Linked List	Linked List, Design
876	Middle of the Linked List	Linked List

Medium

#	Title	Tags
002	Add Two Numbers	Linked List, Math
003	Longest Substring Without Repeating Characters	Hash Table, Two Pointers, String
005	Longest Palindromic Substring	String, Dynamic Programming
015	3Sum	Array, Two Pointers
018	4Sum	Array, Hash Table, Two Pointers
019	Remove Nth Node From End of List	Linked List, Two Pointers
024	Swap Nodes in Pairs	Linked List
031	Next Permutation	Array
046	Permutations	Backtracking
047	Permutations II	Backtracking
054	Spiral Matrix	Array
059	Spiral Matrix II	Array
061	Rotate List	Linked List, Two Pointers
062	Unique Paths	Array, Dynamic Programming
063	Unique Paths II	Array, Dynamic Programming
075	Sort Colors	Array, Two Pointers, Sort
082	Remove Duplicates from Sorted List II	Linked List
086	Partition List	Linked List, Two Pointers
092	Reverse Linked List II	Linked List
094	Binary Tree Inorder Traversal	Hash Table, Stack, Tree
102	Binary Tree Level Order Traversal	Tree, Breadth-first Search
127	Word Ladder	Breadth-first Search
130	Surrounded Regions	Depth-first Search, Breadth-first Search, Union Find
137	Single Number II	Bit Manipulation
142	Linked List Cycle II	Linked List, Two Pointers
143	Reorder List	Linked List
144	Binary Tree Preorder Traversal	Stack, Tree
150	Evaluate Reverse Polish Notation	Stack
153	Find Minimum in Rotated Sorted Array	Array, Binary Search
177	Nth Highest Salary	SQL
178	Rank Scores	SQL
180	Consecutive Numbers	SQL
184	Department Highest Salary	SQL
328	Odd Even Linked List	Linked List

Hard

#	Title	Tags
004	Median of Two Sorted Arrays	Array, Binary Search, Divide and Conquer
023	Merge k Sorted Lists	Linked List, Divide and Conquer, Heap
032	Longest Valid Parentheses	String, Dynamic Programming
084	Largest Rectangle in Histogram	Array, Stack
145	Binary Tree Postorder Traversal	Stack, Tree
295	Find Median from Data Stream	Heap, Design

Contributions

I'm looking for long-term contributors/partners to this repo! Send me PRs if you're interested! See the following:

• Fork this repository to your own GitHub account and then clone it to your local device.
• Add or update file of the repository, then commit and push it to your GitHub repository.
• Submit a pull request with your changes!
• For more details, see CONTRIBUTING.md

Contributors

" If you want to go fast, go alone. If you want to go far, go together. And that's the spirit of teamwork ".