This is a small application which solves a given sudoku using the backtracking method. It has a very simple user interface made with tkinter.

The input - the sudoku puzzle to solve - comes from a file which the user has to provide. The file needs to have the following format:

003020600
900305001
001806400
008102900
700000008
006708200
002609500
800203009
005010300

Whereas the zeros are interpreted as empty fields, which need to be filled by the application in order to solve the sudoku. If the input file is in a wrong format, the application will display a warning.

After the startup of the program it looks like this:

After the input file is loaded, the sudoku can be solved:

Then - depending on wheter the sudoku can be solved - the solved puzzle is displayed:

The solver was tested with some sample inputs, which can be found in the folder test_input_files. Most of the test cases can be found here:

• invalid test cases
• valid test cases