Sudoku Puzzle Generator and Solver

A comprehensive Sudoku application built in C# that generates and solves Sudoku puzzles of different sizes and difficulties. The project includes both a console application and a Windows Forms GUI.

🎯 Features

Core Functionality

• Multiple Grid Sizes: Support for 4x4 and 9x9 Sudoku puzzles
• Difficulty Levels: Easy, Medium, and Hard difficulty settings
• Puzzle Generation: Uses backtracking algorithm to generate valid Sudoku solutions
• Puzzle Creation: Creates puzzles by removing cells based on difficulty level
• Solution Validation: Validates user solutions by checking rows, columns, and sub-boxes

User Interfaces

• Console Application: Text-based interface for quick puzzle generation
• Windows Forms GUI: Interactive graphical interface with visual grid separators

Technical Features

• MVVM Architecture: Clean separation of concerns with Model-View-ViewModel pattern
• Visual Grid Separators: Black lines to clearly delineate 2x2 and 3x3 sub-boxes
• Input Validation: Real-time input filtering and validation
• Professional Documentation: Comprehensive XML documentation throughout the codebase

🏗️ Project Structure

sudoku-puzzle/
├── Suduko/                    # Console Application
│   ├── Model/                 # Data models and business logic
│   │   ├── SudokuBoard.cs     # Sudoku grid representation
│   │   ├── SudokuGenerator.cs # Puzzle generation algorithms
│   │   └── Difficulty.cs      # Difficulty level definitions
│   ├── View/                  # User interface layer
│   │   └── ConsoleView.cs     # Console-based UI
│   ├── ViewModel/             # Business logic coordination
│   │   └── SudokuViewModel.cs # ViewModel for console app
│   ├── Program.cs             # Application entry point
│   └── Suduko.csproj          # Console app project file
├── SudokuGUI/                 # Windows Forms Application
│   ├── Form1.cs               # Main GUI form
│   ├── Form1.Designer.cs      # Form designer file
│   ├── Program.cs             # GUI application entry point
│   └── SudokuGUI.csproj       # GUI project file
├── Suduko.sln                 # Visual Studio solution file
└── README.md                  # Project documentation

🚀 Getting Started

Prerequisites

• .NET 9.0 SDK or later
• Visual Studio 2022 (recommended) or VS Code
• Windows OS (for GUI application)

Installation

1. Clone the repository

   git clone https://github.com/SiD-array/sudoku-puzzle.git
   cd sudoku-puzzle

2. Build the console application

   cd Suduko
   dotnet build

3. Build the GUI application

   cd SudokuGUI
   dotnet build

Usage

Console Application

cd Suduko
dotnet run <size> <difficulty>

Examples:

dotnet run 9 hard      # Generate 9x9 hard difficulty puzzle
dotnet run 4 medium    # Generate 4x4 medium difficulty puzzle

GUI Application

cd SudokuGUI
dotnet run

GUI Features:

1. Select puzzle size (4x4 or 9x9)
2. Choose difficulty level (Easy, Medium, Hard)
3. Click "Generate Puzzle" to create a new puzzle
4. Fill in the empty cells with numbers
5. Click "Validate" to check your solution
6. Click "Show Solution" to see the complete answer

🧩 How It Works

Puzzle Generation Algorithm

1. Solved Board Creation: Uses backtracking algorithm to generate a complete, valid Sudoku solution
2. Puzzle Creation: Randomly removes cells based on difficulty level:
   • Easy: 40% of cells removed
   • Medium: 55% of cells removed
   • Hard: 75% of cells removed

Validation Algorithm

The validation process checks three Sudoku rules:

1. Row Rule: Each row contains numbers 1-9 (or 1-4) without repetition
2. Column Rule: Each column contains numbers 1-9 (or 1-4) without repetition
3. Box Rule: Each 3x3 (or 2x2) sub-box contains numbers 1-9 (or 1-4) without repetition

🎨 GUI Features

Visual Design

• Grid Separators: Black lines clearly separate 2x2 and 3x3 sub-boxes
• Color Coding:
  • Light Gray: Pre-filled cells (read-only)
  • White: Empty cells (editable)
  • Light Yellow: Solution display
• Professional Layout: Clean, spacious design with proper control positioning

User Experience

• Real-time Input Validation: Only allows valid numbers (1-9 for 9x9, 1-4 for 4x4)
• Status Messages: Clear feedback for all user actions
• Responsive Design: Adapts to different puzzle sizes
• Error Handling: Comprehensive error handling with user-friendly messages

🔧 Technical Details

Architecture

• Model Layer: SudokuBoard, SudokuGenerator, Difficulty classes
• ViewModel Layer: SudokuViewModel for business logic coordination
• View Layer: ConsoleView and SudokuForm for user interfaces

Key Classes

• SudokuBoard: Represents the Sudoku grid with methods for manipulation and display
• SudokuGenerator: Handles puzzle generation using backtracking algorithm
• SudokuViewModel: Coordinates between View and Model layers
• SudokuForm: Main GUI form with interactive controls

Data Structures

• Grid Storage: 2D integer array where 0 represents empty cells
• Validation: Uses List<int> for duplicate checking
• Random Generation: Fisher-Yates shuffle algorithm for number randomization

📝 Documentation

The codebase includes comprehensive documentation:

• File Headers: Each file contains author information and description
• XML Documentation: All public methods and properties are documented
• Inline Comments: Complex algorithms and logic are explained
• Code Style: Follows C# coding standards and best practices

🧪 Testing

Manual Testing

• Test both 4x4 and 9x9 puzzle generation
• Verify all difficulty levels work correctly
• Test GUI validation with complete and incomplete puzzles
• Verify visual separators display correctly

Validation Testing

• Generate puzzles and verify they produce valid boards
• Test validation algorithm with correct and incorrect solutions
• Verify input filtering works for both puzzle sizes

🤝 Contributing

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

📄 License

This project is available for educational purposes.

👨‍💻 Author

Siddharth Bhople

• GitHub: @SiD-array
• Date: 18 Oct 2025

🙏 Acknowledgments

• Sudoku puzzle rules and algorithms
• .NET documentation and community
• Visual Studio and development tools
• C# programming best practices

📞 Support

If you encounter any issues or have questions:

1. Check the existing issues in the repository
2. Create a new issue with detailed description
3. Include steps to reproduce any bugs
4. Provide system information (OS, .NET version, etc.)

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Happy Sudoku Solving! 🧩