Sudoku 
======
A sudoku puzzle solver based on depth-first search.

I wrote this little program in 2005 when I was learning to code in C++.

To solve a sudoku of nine elements from 1 to 9, create a text file with the data of it, where '0' or '.' are free places.

The text file should have something like:
0 0 0 2 9 3 0 0 0
0 2 7 0 0 0 3 6 0
0 1 0 0 0 0 0 4 0
4 6 0 0 5 0 0 7 3
0 0 0 0 0 0 0 0 0
7 3 0 0 8 0 0 2 1
0 7 0 0 0 0 0 3 0
0 8 6 0 0 0 1 9 0
0 0 0 7 6 8 0 5 0

Then run the program with the text file as argument.

./Sudoku sudoku.txt


Many thanks to Bert Hubert for his many tips, advice, code reviews and C++ insight.