Sudoku Solver

A c++ sudoku solver.

Build

Clone this repo and build the binaries with:

git clone https://github.com/GabrieleMaurina/sudoku.git
cd sudoku
make

Usage

You can run a simple demo that will solve 20 boards with:

./demo

Or you can run just the solver with:

./sudoku

The solver itself expects a board as a string from the stdin and spits out the solution as a string to the stdout. The easiest way to do it is to get the board from a file like so:

board.txt

0 0 0 0 0 5 0 7 0
1 0 0 0 0 0 0 4 9
5 7 2 0 0 0 0 0 0
0 0 8 0 6 0 0 0 7
0 0 0 0 0 2 3 0 6
9 0 0 5 0 7 0 0 0
7 0 0 0 0 9 0 0 5
0 9 0 0 5 0 0 0 0
0 0 0 0 0 3 0 2 8

Then run: ./sudoku < board.txt > sol.txt

You will get:

sol.txt

8 4 9 3 1 5 6 7 2
1 3 6 2 7 8 5 4 9
5 7 2 4 9 6 8 3 1
3 2 8 9 6 4 1 5 7
4 5 7 1 8 2 3 9 6
9 6 1 5 3 7 2 8 4
7 8 3 6 2 9 4 1 5
2 9 4 8 5 1 7 6 3
6 1 5 7 4 3 9 2 8

Board

The board is just a sequence of characters, where 0 denotes an empty cell and the numbers 1-9 denote the actual numbers from 1 to 9. Any other character is ignored. The numbers fill the board left to right, top to bottom. 20 premade boards are available in the "example" folder.