Local Online Judge

A comprehensive web-based competitive programming platform for hosting local contests and managing programming problems. This system provides a complete online judge experience with user management, contest organization, problem submission, and real-time grading.

⚠️ Security Warning

Important: This system executes user-submitted code directly on the server without sandboxing. Only use this on trusted networks with trusted participants. Do not expose this system to the public internet without proper security measures.

Features

🏆 Contest Management

• Create and manage programming contests with start/end times
• Register participants for contests
• Real-time scoreboards with penalty calculations
• Support for both contest-specific and public problems

📝 Problem Management

• Create and edit programming problems with rich text statements
• Upload test cases via files or direct text input
• Configure time and memory limits per problem
• Bulk import test cases from zip files
• Support for large input/output files

💻 Code Submission & Grading

• Supported Languages: C++ (with g++ compiler)
• Real-time code compilation and execution
• Detailed test case results and scoring
• Submission history and status tracking
• Compile error reporting

👥 User System

• User registration and authentication
• Role-based access control (admin/user/banned)
• Secure password hashing with bcrypt
• Session management

🎯 Admin Panel

• Complete problem and contest management
• User administration
• Test case management with file uploads
• Bulk operations for contest setup

Technology Stack

• Backend: Node.js, Express.js
• Database: MySQL/MariaDB
• Template Engine: Nunjucks
• Frontend: Semantic UI, jQuery
• Authentication: bcrypt, express-session
• File Handling: multer for uploads

Installation

Prerequisites

• Node.js (v14 or higher recommended)
• MySQL or MariaDB database server
• g++ compiler (for C++ code execution)

Setup Instructions

1. Clone the repository:

   git clone https://github.com/CuteMurasame/local-online-judge.git
   cd local-online-judge

2. Install dependencies:

   npm install

3. Set up the database:

   # Create database and user (adjust credentials as needed)
   mysql -u root -p < init_db.sql

4. Configure environment variables (optional):

   export DB_HOST=127.0.0.1
   export DB_USER=root
   export DB_PASSWORD=your_password
   export DB_NAME=cp_platform
   export SESSION_SECRET=your-secure-session-secret

5. Start the server:

   ulimit -s unlimited && node server.js

6. Access the application: Open your browser and navigate to http://localhost:3000

Configuration

The application supports the following environment variables:

Variable	Default	Description
DB_HOST	127.0.0.1	MySQL database host
DB_USER	root	MySQL username
DB_PASSWORD	``	MySQL password
DB_NAME	cp_platform	MySQL database name
SESSION_SECRET	please-change-me	Session encryption secret
PORT	3000	Server port

Usage Guide

For Administrators

1. Create an admin account:

   • Register a regular user account
   • Manually update the database to set role to 'admin'

   UPDATE users SET role = 'admin' WHERE username = 'your_username';

2. Create problems:

   • Navigate to Admin → Problems
   • Click "Create New Problem"
   • Set title, statement, time/memory limits, and scoring
   • Add test cases by uploading files or entering text

3. Set up contests:

   • Navigate to Admin → Contests
   • Create a new contest with start/end times
   • Add problems to the contest
   • Participants can register once the contest is created

For Participants

1. Register an account on the platform
2. Browse available contests on the home page
3. Register for contests you want to participate in
4. Submit solutions during the contest period
5. View results and scoreboard in real-time

Database Schema

The system uses the following main tables:

• users - User accounts and roles
• problems - Problem definitions and metadata
• testcases - Test case files and data
• contests - Contest information and timing
• contest_problems - Problem-contest associations
• submissions - Code submissions and results
• attempts - Submission attempts for scoring
• registrations - Contest participant registrations

API Routes

Public Routes

• GET / - Home page with contests and problems
• GET /login - Login page
• POST /login - User authentication
• GET /register - Registration page (if implemented)
• GET /logout - User logout

Contest Routes

• GET /contests/:id - Contest details
• POST /contests/:id/register - Register for contest
• GET /contest/:cid/problem/:pid - Contest problem view
• GET /contests/:id/scoreboard - Contest scoreboard

Admin Routes

• GET /admin/problems - Problem management
• GET /admin/problems/create - Create new problem
• POST /admin/problems/create - Save new problem
• GET /admin/problems/:id - Edit problem
• POST /admin/problems/:id/edit - Update problem
• POST /admin/problems/:id/add_test - Add test case
• GET /admin/contests - Contest management
• POST /admin/contests/create - Create new contest

Submission Routes

• POST /submit - Submit solution
• GET /submission/:id - View submission details
• GET /submissions - List user submissions

File Structure

local-online-judge/
├── server.js              # Main application server
├── package.json           # Node.js dependencies
├── init_db.sql           # Database schema
├── static/
│   └── style.css         # Custom styles
├── views/                # Nunjucks templates
│   ├── layout.njk        # Base template
│   ├── index.njk         # Home page
│   ├── admin_*.njk       # Admin interfaces
│   ├── contest_*.njk     # Contest pages
│   └── problem_*.njk     # Problem pages
├── data/
│   └── testcases/        # Test case files (created automatically)
└── uploads/              # Temporary upload directory

Development

Adding New Languages

To add support for additional programming languages:

1. Modify the language detection logic in server.js
2. Add compilation and execution commands for the new language
3. Update the submission form to include the new language option
4. Test thoroughly with sample submissions

Extending Features

Common extensions might include:

• Dockerized execution environment for better security
• Additional programming language support
• More sophisticated scoring algorithms
• Team-based contests
• Problem difficulty ratings
• Editorial and solution viewing

Security Considerations

⚠️ Critical Security Notes:

1. Code Execution: User code runs directly on the server without sandboxing
2. Network Security: Only deploy on trusted networks
3. Input Validation: While basic validation exists, additional sanitization may be needed
4. File System: Uploaded files are stored locally without advanced security measures
5. Database: Use strong passwords and limit database access

Recommended Security Enhancements

• Implement Docker containers for code execution
• Add rate limiting for submissions
• Implement file type validation for uploads
• Add CSRF protection
• Use HTTPS in production
• Regular security audits

Contributing

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

Development Guidelines

• Follow Node.js best practices
• Test all new features thoroughly
• Update documentation for new features
• Ensure backward compatibility when possible
• Add proper error handling

License

This project is licensed under the MIT License - see the LICENSE file for details.

Acknowledgments

• Built with Express.js and Node.js
• Uses Semantic UI for styling
• Inspired by competitive programming platforms like Codeforces and AtCoder

Support

For issues, questions, or contributions, please use the GitHub issue tracker or submit a pull request.

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Note: This is a development/educational tool. For production competitive programming platforms, consider using established solutions with proper security measures and sandboxing.