iiitv / algos

Popular Algorithms and Data Structures implemented in popular languages

Algos

Community (college) maintained list of Algorithms and Data Structures implementations.

Implemented Algorithms

Algorithm	C	CPP	Java	Python	Golang	JavaScript	C#
Bin Sort	✅		✅	✅	✅
Binary Search	✅		✅	✅	✅	✅	✅
Breadth First Search		✅	✅	✅
Breadth First Traversal		✅	✅	✅
Coin Change Problem	✅		✅	✅	✅	✅
Counting Sort	✅		✅	✅	✅	✅	✅
Depth First Traversal			✅	✅
Dijkstra Algorithm	✅		✅	✅		✅
Euclidean GCD	✅		✅	✅	✅	✅	✅
Exponentiation by Squaring	✅		✅	✅	✅	✅
Heap Sort	✅	✅	✅	✅		✅
Insertion Sort	✅	✅	✅	✅	✅	✅	✅
k-NN				✅
Largest Sum Contiguous Subarray	✅		✅	✅	✅	✅
Linear Regression				✅
Linear Search	✅		✅	✅	✅	✅	✅
Longest Common Subsequence	✅		✅	✅	✅	✅
Longest Palindromic Substring		✅	✅	✅	✅	✅
Merge Sort	✅		✅	✅	✅	✅	✅
Modular Exponential	✅		✅	✅	✅	✅
Nth Fibonacci Number	✅		✅			✅
N-Queen Problem		✅	✅	✅	✅
Prime Factor	✅		✅	✅	✅	✅
Prims	✅		✅		✅	✅
Quick Select	✅		✅	✅
Quicksort	✅		✅	✅	✅	✅	✅
Radix Sort	✅		✅	✅
Rod Cutting Problem	✅		✅	✅	✅	✅
Shell Sort		✅	✅	✅	✅	✅	✅
Sieve of Eratosthenes	✅		✅	✅	✅	✅
Sleep Sort		✅	✅	✅	✅

Implemented Data Structures

Data Structure	C	CPP	Java	Python	Golang	JavaScript	C#
AVL Tree	✅		✅
Binary Search Tree			✅	✅	✅
Linked List	✅		✅	✅	✅	✅	✅
Queue		✅	✅	✅
Stack	✅		✅	✅	✅	✅	✅
Trie		✅	✅		✅		✅

How to run them

Language	Steps
C	gcc [filename.c] ./a.out # unix a.exe # windows
CPP	g++ [filename.cpp] ./a.out # unix a.exe # windows
Java	javac [filename.java] java [filename]
Python	python [filename.py]
Golang	go run [filename.go]
JavaScript	node [filename.js]
C#	mcs [filename.cs] mono [filename.exe]

Resources

• Algorithms - Learneroo
• Awesome-Algorithms
• Algorithms List - GeeksforGeeks
• Intro to Algorithms - Khan Academy
• Popular Data Structures and Algorithms - Codechef
• Stanford-ACM-Codes - A list of codes written by previous Stanford ACM team members and coaches.
• Data Structures and Algorithms - A user ranked list of online tutorials to learn Data Structures and Algorithms online.

Contributing

See CONTRIBUTING.md.

If you plan to suggest a new algorithm or DS, please make sure to read the guidelines.

Credits

Idea by @Monal5031

Project Maintainers

• Avi Aryan
• Pratyush Singh

Only project maintainers should merge a PR. Other members can add their reviews to a PR but the merging should be done by only a project maintainer.

algos's Issues

Merge Sort

https://www.khanacademy.org/computing/computer-science/algorithms/merge-sort/a/overview-of-merge-sort

Add me to repo

It would be good if one raises an issue for adding as contrib rather than commenting in an ongoing PR, because it is not referenced to the PR.

Breadth First Search in a Graph [Java]

https://en.wikipedia.org/wiki/Breadth-first_search

Sieve of Eratosthenes [C]

https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes
Algorithm to find prime numbers till a number N

Insertion Sort [Python]

https://en.wikipedia.org/wiki/Insertion_sort

Binary search on sorted array

http://quiz.geeksforgeeks.org/binary-search/

Selection Algorithm [C]

Suppose you want to find the kth position element in a sorted list without sorting the list, Need to find the median in a Large Data set after Sorting. In these places Selection algorithm can be used.

Split the existing issues based on language

Modular Exponential [Python]

http://www.geeksforgeeks.org/modular-exponentiation-power-in-modular-arithmetic/

Data structures in this list?

I think we should include DS in this list too. I mean they are very related to the algorithms and are often used in algorithms. Examples - implementation of Stack, Queue, Heap etc.

Please post your views regarding this. @singhpratyush @Monal5031 @yashLadha @aashutoshrathi @jsroyal

Coin Change Problem [C]

Given a value N, if we want to make change for N cents, and we have infinite supply of each of S = { S1, S2, .. , Sm} valued coins, how many ways can we make the change? The order of coins doesn’t matter.

For example, for N = 4 and S = {1,2,3}, there are four solutions: {1,1,1,1},{1,1,2},{2,2},{1,3}. So output should be 4. For N = 10 and S = {2, 5, 3, 6}, there are five solutions: {2,2,2,2,2}, {2,2,3,3}, {2,2,6}, {2,3,5} and {5,5}. So the output should be 5.

Add a PULL REQUEST TEMPLATE

It should specifically remind people to have a look at the CONTRIBUTING guidelines before submitting their patch. Also some keys points from the guidelines should be listed out.

Example: https://github.com/aviaryan/awesome-no-login-web-apps/blob/master/PULL_REQUEST_TEMPLATE.md

Depth First Traversal [Java]

http://www.geeksforgeeks.org/depth-first-traversal-for-a-graph/

The Longest Common Subsequence [C]

LCS Problem Statement: Given two sequences, find the length of longest subsequence present in both of them. A subsequence is a sequence that appears in the same relative order, but not necessarily contiguous. For example, “abc”, “abg”, “bdf”, “aeg”, ‘”acefg”, .. etc are subsequences of “abcdefg”. So a string of length n has 2^n different possible subsequences.

Examples:
LCS for input Sequences “ABCDGH” and “AEDFHR” is “ADH” of length 3.
LCS for input Sequences “AGGTAB” and “GXTXAYB” is “GTAB” of length 4.

Counting Sort [Java]

A popular algorithm used for sorting under specific constraints but if constraints were followed, It is the one of the fastest sort

www.geeksforgeeks.org/counting-sort/

Submit a sample implementation of an algorithm to serve as a complete example

The algorithm can be anything.
Language should be one of Java, Python, C or C++.

Trie [Java]

https://en.wikipedia.org/wiki/Trie

Euclidean GCD [C]

Finding gcd of two numbers using Eucledian Algorithm. (Recursive and non-recursive both can be implemented).
EDIT:
Link: https://en.wikipedia.org/wiki/Euclidean_algorithm

Kadane's Algorithm (Largest Sum Contiguous Subarray problem) [CPP]

A popular Dynamic programming algorithm to find a largest sum contiguous subarray.

https://kartikkukreja.wordpress.com/2013/06/17/kadanes-algorithm/

Possible Algo. List and Difficulty level

We can compile a possible list of Algorithms to be implemented so that a person attempting as a beginner will not have much problem.
Further, I guess it would be nice to assign the work to implement the algorithms according to the difficulty level. Like a person who is familiar with coding will not attempt beginner level programs and maybe leave them for the new one's. Also, a time constraint would also be a good thing to add so that someone else who is ready to do it will get that chance.

Integrate Codacy

Codacy has a good PR integration which comments design issues in the code directly in the PRs.
I think we should be using it.

Coding Guidelines

Adding a .md file discussing the guidelines for solutions would be helpful.

Insertion Sort [C]

https://en.wikipedia.org/wiki/Insertion_sort
Implementation would be same in c and c++

Breadth First Search in a Graph [Python]

https://en.wikipedia.org/wiki/Breadth-first_search

Stack [JAVA]

https://en.wikipedia.org/wiki/Stack_(abstract_data_type)

Following Functionalities I will add:

• Display stack elements
• Push (Adding element to top of stack)
• Pop (Removing element from top of stack)
• Peek
• Get size

Will create a separate class for it and test in Main class.
Any suggestions over any particular thing I should use?

Euclidean GCD [Java]

Define a merge policy

We need a merge policy to fix how we are going to merge PRs. Here's my proposal -

1. One squashed commit merge with PR.
2. Even if PR contains multiple type of changes, it should reflect only a single topic and Rule 1 shall still withhold on it.

Why squashed merge ?

It preserves both the author as well as the committer, something that can be very useful.
Also one commit per PR provides the cleanest commit history possible.

---

@singhpratyush views?

Add Java skeleton code to guidelines

Add Java skeleton code at https://github.com/iiitv/algos/blob/master/CONTRIBUTING.md#samples

This issue is up for grabs. Anyone can assign themselves and start working on this.

Quicksort [C]

https://en.wikipedia.org/wiki/Quicksort

Largest Sum Contiguous Subarray problem [Java]

find the sum of contiguous subarray within a one-dimensional array of numbers.

Binary Search [python]

Merge Sort [C]

https://en.wikipedia.org/wiki/Merge_sort

Add Python sample code

Add a Python sample/skeleton code in the CONTRIBUTING file .. https://github.com/iiitv/algos/blob/master/CONTRIBUTING.md#samples

Anyone who wants to work on this, please assign yourself.

k-NN Algorithm [Python]

https://en.wikipedia.org/wiki/K-nearest_neighbors_algorithm

Sieve of Erastosthenes [Python]

https://en.wikipedia.org/wiki/Sieve_of_Eratosthenes

Merge Sort [CPP]

Linear Search [C]

https://en.wikipedia.org/wiki/Linear_search

Binary Search [C]

Euclidean GCD [CPP]

Heap Sort [C]

https://en.wikipedia.org/wiki/Heapsort

Binary Search [Java]

Stack [Python]

https://en.wikipedia.org/wiki/Stack_(abstract_data_type)

Require following functionalities -

• Print
• Push
• Pop
• Peek
• Get size

Create a class and add example usage in single file.

A* Search [Java]

https://en.wikipedia.org/wiki/A*_search_algorithm

Exponentation by squaring [C]

https://en.wikipedia.org/wiki/Exponentiation_by_squaring

It is very much efficient algorithm to calculate x raised to power k.

Edit: time complexity is O( (nlogx) ^ k)

Backtracking algorithm (N-Queen Problem) [CPP]

A general solution of the N-Queen problem (any board of n X n) in C++ with backtracking.

https://en.wikipedia.org/wiki/Eight_queens_puzzle

Prime Factors of a Number [C]

https://en.wikipedia.org/wiki/Prime_factor

QuickSort [java]

https://en.wikipedia.org/wiki/Quicksort

Euclidean GCD [Python]

Mo's Algorithm [CPP]

Explanation link: http://codeforces.com/blog/entry/43230

Add more helpful resources to README

Please add more algorithm lists / tutorial lists / related materials etc to the Resources section of the README.