Sudoku Game in C (Playable with the keyboard!)

Welcome to the Sudoku Game repository! This project is a simple yet challenging Sudoku game built entirely in the C programming language. The game offers three difficulty levels, allowing players to choose their preferred level of challenge.

Sudoku Rules

Sudoku is a logic-based, combinatorial number-placement puzzle. The objective is to fill a 9x9 grid with digits so that each column, each row, and each of the nine 3x3 subgrids (also called "boxes") contain all of the digits from 1 to 9. The puzzle starts with some cells already filled in, and the difficulty of the puzzle depends on the number of cells initially filled and their arrangement.

Basic Rules:

1. Each row must contain the digits 1 to 9 without repetition.
2. Each column must contain the digits 1 to 9 without repetition.
3. Each of the nine 3x3 subgrids must contain the digits 1 to 9 without repetition.

How to Play

1. Choose Difficulty: The game offers three difficulty levels—easy, medium, and hard. The difficulty level determines the number of pre-filled cells and the complexity of the puzzle.
2. Fill the Grid: Using the numbers 1 to 9, fill the empty cells on the grid. Ensure that each number appears only once in each row, column, and 3x3 subgrid.
3. Solve the Puzzle: Continue filling in numbers until the entire grid is complete. The game will verify if the solution is correct.

How to Compile and Run

To compile and run the Sudoku game, follow these steps:

1. Clone the Repository:

   git clone https://github.com/pinedah/sudoku_in_c.git
   cd sudoku-game

2. Compile the Game:

   gcc -o sudoku sudoku.c

3. Run the Game:

   ./sudoku

References for Sudoku Generation Algorithm

The algorithm provided for generating a Sudoku grid involves several well-known concepts and techniques commonly used in Sudoku puzzle generation and solving. Here are the main concepts and some references:

1. Backtracking Algorithm:

   • The fillGrid function uses a backtracking algorithm to fill the grid with a valid Sudoku solution. Backtracking is a general algorithm for finding all (or some) solutions to computational problems, notably used in constraint satisfaction problems like Sudoku.
   • Reference: "Backtracking" on Wikipedia

2. Constraint Propagation:

   • The isSafe function checks if placing a number violates any Sudoku rules. This is a form of constraint propagation, ensuring that constraints (rules) are satisfied.
   • Reference: "Constraint satisfaction problem" on Wikipedia

3. Randomization:

   • The grid is filled with random numbers from 1 to 9, and cells are removed randomly to create the puzzle. Randomization helps in generating different puzzles each time.
   • Reference: "Sudoku" on Wikipedia, especially the "Construction" section

4. Sudoku Puzzle Difficulty:

   • The number of cells removed to set the difficulty level of the puzzle is based on typical practices in Sudoku puzzle creation. More cells removed generally means a higher difficulty level.
   • Reference: "Sudoku" on Wikipedia, particularly the sections discussing puzzle generation and difficulty

These references provide a comprehensive background on the techniques and concepts used in the provided algorithm for generating a Sudoku grid with varying difficulty levels.

Note

I built this Sudoku game because I saw my girl, playing it once and told her I could build it. This project is dedicated to her and her love for Sudoku.

Enjoy the game!

License

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