MyCSES - CSES Problem Set Solutions

This repository contains solutions to problems from the CSES Problem Set, implemented in C++. The CSES Problem Set is a collection of competitive programming practice problems that cover various algorithmic topics.

🎃 Participating in Hacktoberfest 2025! We welcome quality contributions from the community. Check out our Contributing Guidelines to get started.

👨‍💻 Maintainer

Kunal Sharma
IIT Jammu

🤝 Contributing

We encourage contributions from the competitive programming community! Whether you're a beginner or an expert, there are many ways to contribute:

🐛 Report bugs or suggest improvements
💡 Add new problem solutions
📚 Improve documentation
🎯 Optimize existing solutions
✨ Add explanatory comments to complex algorithms

New to open source? Look for issues labeled good first issue to get started!

👉 Read our Contributing Guide for detailed instructions on how to contribute.

📋 Code of Conduct

This project follows the Contributor Covenant Code of Conduct. By participating, you are expected to uphold this code. Please report unacceptable behavior to the maintainers.

📁 Repository Structure

The solutions are organized by problem categories:

├── 1_introductory_problems/    # Basic algorithmic problems
├── 2_sorting_searching/        # Sorting and searching algorithms
├── 3_dp/                      # Dynamic programming problems
├── 7_mathematics/             # Mathematical problems
├── .builds/                   # Build configurations
└── .vscode/                   # VS Code settings

🧩 Problem Categories

1. Introductory Problems

Two Sets - Partitioning numbers into two equal sum sets
Gray Code - Generating Gray code sequences
Apple Division - Minimizing difference in apple weight distribution
Chessboard and Queens - N-Queens problem variant
Coin Piles - Mathematical puzzle with coin removal rules
Bit Strings - Counting binary strings

2. Sorting and Searching

Apartments - Matching applicants to apartments
Movie Festival - Activity selection problem
Collecting Numbers - Array manipulation problems
Minimum Coin Sum - Finding smallest unrepresentable sum

3. Dynamic Programming

Minimizing Coins - Classic coin change problem

4. Graph Algorithms

Counting Rooms
Labyrinth - Finding path from A to B
Shortest Routes II - Finding shortest path from $u$ to $v$ for $q$ different queries

7. Mathematics

Exponentiation 2 - Fast exponentiation with modular arithmetic
Sum of Divisors - Mathematical series calculation
Creating Strings - Combinatorics with factorial calculations
Next Prime - Finding next prime
Christmas Party - Finding derangement of $n$ elements

🔧 Implementation Details

Language & Standards

Language: C++
Compiler: Standard C++ compiler
Libraries: STL (Standard Template Library)

Common Patterns Used

// Standard template used across solutions
#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
#define mod 1000000007

// Fast I/O optimization
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);

Key Algorithmic Techniques

Fast Exponentiation: Binary exponentiation for efficient power calculation
Modular Arithmetic: Using MOD = 1000000007 for large number calculations
Dynamic Programming: Bottom-up and memoization approaches
Greedy Algorithms: Activity selection and optimization problems
Bit Manipulation: Efficient subset generation and Gray codes
Mathematical Formulas: Combinatorics and number theory

🚀 How to Use

Clone the repository:

git clone https://github.com/ks-iitjmu/MyCSES.git
cd MyCSES

Compile a solution:

g++ -o solution category/problem_name.cpp

Run the solution:
```
./solution < input.txt
```

📊 Problem Solving Approach

Each solution follows a structured approach:

Problem Analysis: Understanding constraints and edge cases
Algorithm Selection: Choosing optimal time/space complexity approach
Implementation: Clean, readable C++ code
Optimization: Fast I/O and efficient algorithms for competitive programming

🏆 Competitive Programming Features

Fast I/O: All solutions use optimized input/output
Type Definitions: Consistent use of typedef long long ll
Modular Arithmetic: Proper handling of large numbers
Edge Case Handling: Robust solutions for boundary conditions
Clean Code: Readable and well-structured implementations

📈 Progress Tracking

✅ Introductory Problems: Multiple problems solved
✅ Sorting and Searching: Core algorithms implemented
✅ Dynamic Programming: Foundation problems completed
✅ Mathematics: Advanced mathematical concepts covered

🌟 Contributors

Thanks to all the amazing contributors who have helped improve this repository!

Want to contribute? Check out our Contributing Guidelines!

🎃 Hacktoberfest

This repository participates in Hacktoberfest! We welcome quality contributions during October and throughout the year.

How to participate:

Look for issues labeled hacktoberfest
Check out good first issue labels for beginner-friendly tasks
Read our Contributing Guidelines
Submit quality pull requests
Help review other contributions

Contribution Ideas:

Solve new CSES problems
Optimize existing solutions
Add detailed comments and explanations
Improve documentation
Add test cases
Create problem difficulty classifications

🔗 Useful Links

CSES Problem Set
CSES Book - Competitive Programming Handbook

📝 Notes

Solutions are optimized for competitive programming contests
Time complexity is prioritized for large input constraints
Code follows standard competitive programming conventions
All solutions have been tested against CSES judge system

🚀 Getting Started for Contributors

Fork this repository
Clone your fork: git clone https://github.com/YOUR_USERNAME/MyCSES.git
Create a branch: git checkout -b feature/problem-name
Add your solution following our guidelines
Test thoroughly against CSES judge
Submit a pull request

📞 Support

🐛 Found a bug? Create an issue
💡 Have a suggestion? Start a discussion
📧 Need help? Check our Contributing Guide

📜 License

This project is open source and available under the MIT License.

Feel free to explore the solutions, contribute, and use them for learning purposes. Happy coding! 🚀

⭐ Star this repository if you find it helpful!

MyCSES

Install / Use

README