Terminal Sudoku

A command-line Sudoku puzzle game written in C. This game generates random Sudoku puzzles with varying difficulty levels and provides an interactive terminal-based interface for solving them.

Features

• Random Puzzle Generation: Generates unique Sudoku puzzles with guaranteed single solutions
• Multiple Difficulty Levels: Choose from Easy (40 removed cells), Medium (50 removed cells), or Hard (54 removed cells)
• Interactive Gameplay: Navigate the board with arrow keys or WASD controls
• Cross-Platform Compatibility: Works on Windows, Linux, and macOS
• Visual Cursor: Highlights your current position on the board
• Input Validation: Prevents modification of original puzzle numbers
• Win Detection: Automatically detects when you've successfully completed the puzzle

How to Play

1. Navigation:

   • Use arrow keys or WASD to move the cursor around the board
   • Current position is shown in brackets [X]

2. Number Input:

   • Press numbers 1-9 to place a number in the current cell
   • Press 0 to clear a cell
   • You can only modify empty cells (original puzzle numbers are protected)

3. Game Controls:

   • Press 'Q' or 'q' to quit the game at any time

4. Winning:

   • Fill all empty cells with valid numbers according to Sudoku rules
   • The game will automatically detect when you've won

Sudoku Rules

• Each row must contain the digits 1-9 with no repetition
• Each column must contain the digits 1-9 with no repetition
• Each of the nine 3×3 sub-grids must contain the digits 1-9 with no repetition

Building and Running

Prerequisites

• Microsoft Visual Studio Build Tools or Visual Studio (for Windows)
• C compiler (gcc, clang, or MSVC)

Windows (Visual Studio Developer Command Prompt)

1. Open VS Developer Command Prompt:

   • Search for "Developer Command Prompt for VS" in the Start menu
   • Or open a regular command prompt and run vcvars64.bat (usually located in C:\Program Files\Microsoft Visual Studio\2022\Community\VC\Auxiliary\Build\)

2. Navigate to project folder:

   cd path\to\TerminalSudoku

3. Compile the program:

   cl sudoku.c /Fe:sudoku.exe

4. Run the game:

   sudoku.exe

Game Interface

Sudoku Puzzle
Use arrow keys or WASD to move, 1-9 to place numbers, 0 to clear. 'q' to quit.
Current position: [1,1]

[5] .  . | .  .  . | .  8  . 
 .  2  . | .  .  . | .  .  6 
 .  .  . | 5  .  . | .  .  . 
-----------------------
 .  .  . | .  1  . | .  .  . 
 .  .  4 | .  .  . | 2  .  . 
 .  .  . | .  7  . | .  .  . 
-----------------------
 .  .  . | .  .  2 | .  .  . 
 1  .  . | .  .  . | .  4  . 
 .  6  . | .  .  . | .  .  7 

• Numbers from the original puzzle are displayed normally
• Empty cells show as dots (.)
• Your current position is highlighted with brackets [X]
• User-entered numbers are displayed clearly

Technical Details

Algorithm Features

• Puzzle Generation: Uses a backtracking algorithm to generate complete valid Sudoku solutions
• Unique Solution Guarantee: Ensures each generated puzzle has exactly one solution by systematically removing numbers and validating uniqueness
• Optimized Solver: Implements efficient backtracking with constraint checking
• Cross-Platform Input: Handles different keyboard input methods across operating systems

Code Structure

• isValid(): Validates number placement according to Sudoku rules
• solveSudoku(): Backtracking solver for puzzle generation
• countSolutions(): Counts possible solutions to ensure puzzle uniqueness
• generatePuzzle(): Creates new puzzles with specified difficulty
• gameLoop(): Main interactive game loop
• checkWin(): Validates complete puzzle solution

Difficulty Levels

• Easy (1): 40 numbers removed from complete puzzle
• Medium (2): 50 numbers removed from complete puzzle
• Hard (3): 54 numbers removed from complete puzzle

Requirements

• C compiler with standard library support
• Terminal/Command prompt
• Windows: Uses conio.h for keyboard input
• Linux/macOS: Uses termios.h for cross-platform keyboard input

License

This project is open source. Feel free to modify and distribute as needed.

Contributing

Contributions are welcome! Please feel free to submit pull requests or open issues for bugs and feature requests.