Exercise 13

Problem

For this exercise, we want to code a program sudoku.py that solves a Sudoku game.

The program should work as follow:

$ python sudoku.py examples/simple.txt

If simple.txt has those lines:

$ cat examples/simple.txt
53. .7. ...
6.. 195 ...
.98 ... .6.

8.. .6. ..3
4.. 8.3 ..1
7.. .2. ..6

.6. ... 28.
... 419 ..5
... .8. .79

The program should give:

$ python sudoku.py examples/simple.txt
534 678 912
...
... the Sudoku solved! ...

Help

Start by writing some code that checks the validity of a solution.