Killer Sudoku Solver (C + Raylib)

Overview

This project is a Killer Sudoku solver implemented in C with two interfaces:

• GUI Mode using Raylib for interactive puzzle creation and solving
• Terminal Mode for file-based input and step-by-step solving with debug logs

Both modes share a common backend solver based on backtracking with cage constraints.

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Features

• Create custom Killer Sudoku puzzles using GUI
• Solve puzzles instantly or step-by-step (terminal debug mode)
• Support for cage constraints (sum-based regions)
• Clean modular structure with reusable solver logic
• Multiple execution modes via a launcher

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Project Structure

sudoku-solver/
│
├── launcher.c          # Entry point (mode selection)
├── Makefile            # Build automation
├── .gitignore
│
└── source_code/
    ├── gui.c           # GUI implementation (Raylib)
    ├── grid.c          # Grid initialization and display
    ├── f_all.c         # Terminal solver
    ├── solver.c        # Backtracking solver
    ├── validator.c     # Sudoku constraints
    ├── cage.c          # Cage structures
    ├── cage_rules.c    # Cage validation logic
    ├── parser.c        # File input parser
    └── headers (.h)

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Build Instructions

Prerequisites

Before building, make sure you have the following installed:

• GCC (C compiler)
• Raylib — required for GUI mode
  • Windows: Download from https://www.raylib.com and follow setup instructions
  • Linux: sudo apt install libraylib-dev
  • Mac: brew install raylib

Using Makefile (recommended)

make

Manual compilation (optional)

GUI:

gcc source_code/gui.c source_code/grid.c source_code/solver.c source_code/validator.c source_code/cage.c source_code/cage_rules.c -o gui_app -lraylib -lopengl32 -lgdi32 -lwinmm

Terminal:

gcc source_code/f_all.c source_code/grid.c source_code/solver.c source_code/validator.c source_code/cage.c source_code/cage_rules.c source_code/parser.c -o terminal_app

Launcher:

gcc launcher.c -o launcher

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Running the Project

Run the launcher:

./launcher

Choose mode:

• 1 → Terminal Mode
• 2 → GUI Mode

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Terminal Mode

• Supports manual or file input
• Displays solving steps (debug mode enabled)
• Example input file path:

source_code/input.txt

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GUI Mode

• Draw cages interactively
• Assign sums
• Press S to solve
• Displays solution visually on grid

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Debug Mode

• Enabled in terminal mode
• User Controlled:

prompted to choose:
    -> 1 for enabling debug control
    -> 0 for disabling debug control

• GUI runs with debug disabled for clean output

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Technologies Used

• C (core logic)
• Raylib (GUI rendering)
• Makefile (build system)

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Future Improvements

• Puzzle generator
• Difficulty levels
• Save/load puzzles from GUI
• Animated solving visualization

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Authors

Name	Roll No.	Contribution
Busa Srinivas	B25EE1010	Cage structures (cage.c), terminal input handling (f_all.c)
Sourav Mallick	B25ME1079	Parser (parser.c), backtracking solver (solver.c)
S Mithush Kumar	B25PH1012	Launcher, Makefile, cage_rules.c, conflict resolution & integration
Mohammad Zeba	B25CS1041	GUI interface (gui.c), grid initialization (grid.c), debugging
Varri Sushmitha	B25ME1087	Sudoku rule validation, terminal input conditions (f_all.c)
Sweccha Eldhas	B25EE1014	Step-by-step solve printing, number validation (validator.c)

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