🧩 Sudoku Game

A fully functional, interactive Sudoku game built with React + Vite and deployed via Vercel.
Includes smart features like cell highlighting, input validation, undo, hints, and a victory animation!

🚀 Play it live here!

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✨ Features

• ✅ Sudoku board with random puzzle generation
• 🎯 Real-time input validation (shows wrong numbers)
• 🎯 Multiple difficulty levels
• 🔄 Undo feature
• 💡 Hint system
• 🟨 Highlight matching numbers
• 🧠 Victory detection and animation
• 📱 Responsive design – works on mobile too!

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🧠 How Puzzle Generation Works

This game includes a fully custom-built Sudoku puzzle engine that guarantees validity and uniqueness for each board.

Step-by-Step:

1. Solved Board Generation

   • A full Sudoku board is filled using a backtracking algorithm.
   • The board is randomized but legal, forming a valid solution.

2. Deep Copy

   • Before removing values, the solution board is deeply copied to preserve the final answer for:
     • Hint logic
     • Final victory validation

3. Clue Removal With Uniqueness Guarantee

   • A list of all cell positions is generated and shuffled.
   • For each cell:
     • Temporarily remove its value.
     • Count total solutions using a solution-counter function.
     • Solution-counter function counts total number of possible solutions of a puzzle.
     • Only remove it permanently if the board still has exactly one solution.

4. Difficulty Control

   • The engine removes clues based on desired difficulty:
     • Easy: ~35–40 clues
     • Medium: ~28–34 clues
     • Hard: ~22–27 clues
   • However, the engine may stop early if further removals break uniqueness — preserving solvability.

✅ Guarantees

• Every puzzle has exactly one valid solution
• Clue removal is optimized to make the board as challenging as possible without ambiguity

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🛠️ Tech Stack

• React
• Vite
• Vercel
• Custom JS game logic (Sudoku engine, backtracking solver, validation, UI state)

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🚀 Getting Started

Clone and run locally:

git clone https://github.com/u-cant-see-me/Sudoku.git
cd Sudoku
npm install
npm run dev

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🙌 Acknowledgements

Made with ❤️ by Yash Gupta
Thanks to the many online Sudoku tools and tutorials that inspired the logic design. Design, highlighting interactions, and several UI features were inspired by sudoku.com. All logic — including board generation, uniqueness validation, hint systems, and animations — was implemented entirely from scratch.