LeetCode-Solutions

Got stuck in a LeetCode question? This repository will help you by providing approach of solving the problems from LeetCode platform.

Contributors helped us in providing these Awesome solutions.

If you want to contribute, please create a Pull Request. If you are new to Github please check pull request procedure ---> PR process

Check out ---> Sample PR

There are new LeetCode questions every week. I'll keep updating for full summary and better solutions.
For more challenging problem solutions, you can also see our HackerRank-Solutions, ProjectEuler repositories.
Hope you enjoy the journey of learning data structures and algorithms.
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Check out -> Learning Resources

Algorithms

Bit Manipulation
Array
String
Linked List
Stack
Queue
Heap
Tree
Hash Table
Math
Two Pointers
Sort
Recursion
Binary Search
Binary Search Tree
Breadth-First Search
Depth-First Search
Backtracking
Dynamic Programming
Greedy
Graph
Geometry
Simulation
Design
Concurrency

Bit Manipulation

#	Title	Solution	Time	Space	Difficulty	Note
0136	Single Number	Java Python	O(n)	O(1)	Easy	Using XOR
0260	Single Number III	Python	O(n)	O(1)	Medium
0520	Detect Capital Use	Python	O(n)	O(1)	Easy

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Array

#	Title	Solution	Time	Space	Difficulty	Tag
56	Merge Intervals	Python	O(nlogn)	O(n)	Medium	Intervals
268	Missing Number	Java	O(n)	O(1)	Easy	Array
697	Degree of an Array	Java	O(n)	O(n)	Easy	Array
1089	Duplicate Zeroes	JavaScript	O(n)	O(n)	Easy	Array
1502	Can Make Arithmetic Progression From Sequence	Java	O(n)	O(1)	Easy	Array

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String

#	Title	Solution	Time	Space	Difficulty	Note
383	Ransom Note	Java	O(1)	O(n)	Easy	Character Count
151	Reverse Words in a String	Java	O(1)	O(n)	Medium
520	Detect Capital Use	Java	O(n)	O(1)	Easy

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Linked List

#	Title	Solution	Time	Space	Difficulty	Tag
002	Add Two Numbers	Java	O(n)	O(n)	Medium	Math
141	Linked List Cycle	Java	O(n)	O(1)	Easy	Slow-Fast Pointers
146	LRU Cache	C++	O(1)	O(k)	Medium	Hash Map

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Stack

#	Title	Solution	Time	Space	Difficulty	Tag	Note
020	Valid Parentheses	Python	O(n)	O(n)	Easy	Stack

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Tree

#	Title	Solution	Time	Space	Difficulty	Tag
094	Binary Tree Inorder Traversal	Java	O(n)	O(logn)	Medium	Binary Tree, Stack, HashTable
101	Symmetric Tree	Java	O(n)	O(n)	Easy	Tree, Breadth-first Search, Depth-first Search
144	Binary Tree Preorder Traversal	Java	O(n)	O(logn)	Medium	Binary Tree, Stack
145	Binary Tree Postorder Traversal	Java	O(n)	O(logn)	Hard	Binary Tree, Stack
103	ZigZag Level Order	JavaScript	O(n)	O(n)	Medium	Binary Tree
129	Sum Root to Leaf Numbers	Java	O(n)	O(logn)	Medium	Binary Tree, Depth First Search
307	Range Sum Query - Mutable	Java	O(logn)	O(n)	Medium	Segment Tree
919	Complete Binary Tree Inserter	Java	O(n)	O(n)	Medium	Tree
124	Binary Tree Maximum Path Sum	C++	O(n)	O(n)	Hard	Tree
1028	Recover a Tree From Preorder Traversal	C++	O(n)	O(n)	Hard	Tree

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Hash Table

#	Title	Solution	Time	Space	Difficulty	Video Explanation
001	Two Sum	Java Python	O(N)	O(N)	Easy	Tutorial
242	Valid Anagram	Java	O(n)	O(1)	Easy	Tutorial
146	LRU Cache	Java			Medium

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Two Pointer

#	Title	Solution	Time	Space	Difficulty	Tag	Note
005	Longest Palindromic Substring	Python	O(N^2)	O(N)	Medium		Expand the Wings

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Math

#	Title	Solution	Time	Space	Difficulty	Tag
204	Count Primes	C++	O(n(log(logn)))	O(n)	Easy	Math
168	Excel Sheet Column Title	C++	O(n)	O(n)	Easy	String
007	Reverse Integer	Java C++	O(n)	O(n)	Easy	Math

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Breadth-First Search

#	Title	Solution	Time	Space	Difficulty	Tag	Note
1284	Minimum Number of Flips to Convert Binary Matrix to Zero Matrix	C++	O(m n * 2 ^ (m * n))*	O(2 ^ (m n))*	Hard	BFS

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Depth-First Search

#	Title	Solution	Time	Space	Difficulty	Tag	Note
1463	Cherry Pickup II	C++	O(n m)*	O(n m)*	Hard	DFS

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BackTracking

#	Title	Solution	Time	Space	Difficulty	Tag	Note
037	Sudoku Solver	C++	O(n^2)	O(1)	Hard	Hash Table
980	Unique Paths III	C++	O(R C * 2 ^ (R * C))*	O(R C)*	Hard	DFS, Memoization

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Dynamic Programming

#	Title	Solution	Time	Space	Difficulty	Tag
416	Partition Equal Subset Sum	C++	O(n^2)	O(n^2)	Medium	DP
56	Wildcard Matching	Python	O(n^2)	O(n^2)	Hard
343	Integer Break	C++	O(n^2)	O(n)	Medium
139	Word Break	Python	O(n^3)	O(n)	Medium	DP
1092	Shortest Common Supersequence	C++	O(n^2)	O(n^2)	Hard	DP

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Binary Search

#	Title	Solution	Time	Space	Difficulty	Tag	Note
278	First Bad Version	Java JavaScript	O(logn)	O(1)	Easy		Binary Search
33	Search in Rotated Sorted Array	Python	O(logn)	O(1)	Medium		Binary Search

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Graph

#	Title	Solution	Time	Space	Difficulty	Tag	Note
1042	Flower Planting with No Adjacent	Python	O(V+E)	O(2V+E)	Medium	Graph	Graph Coloring

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Learning Resources

1.) Cracking the Coding Interview

2.) Data Structures and Algorithms Made Easy in Java

3.) Data Structure and Algorithmic Thinking with Python

4.) Grooking Algorithms

5.) Dynamic Programming for Coding Interviews

DISCLAIMER: This above mentioned resources have affiliate links, which means if you buy one of the product from my links, I’ll receive a small commission. This helps support the channel and allows us to continue to add more tutorial. Thank you for the support!

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Authors

Gourav Rusiya

Contributors

Name	Country	Programming Language	Where to find you ^{(add all links to your profiles eg on Hackerrank, Codechef, LeetCode...)}
Gourav R	India	Java	codedecks Hackerrank
Lokendra Bohra	India	Python	Leetcode Hackerrank
Yuri Spiridonov	Russia	Python	Twitter Leetcode Hackerrank
Naveen Kashyap	India	Javascript	Twitter Leetcode
Rudra Mishra	India	C++	Twitter Leetcode
Sachin Singh Negi	India	Python	Twitter Leetcode Hackerrrak
Girish Thatte	India	Java	Leetcode Hackerrank Codechef