Q: How do we use constraint propagation to solve the naked twins problem?
A: The Naked Twins is another constraint of Sudoku rule. Therefore we should put it in the procedure of the puzzle reduce, similar to the "Only choice" and the "Elimination", and propagate it in each iteration.

Q: How do we use constraint propagation to solve the diagonal sudoku problem?
A: In fact, the diagonal sudoku problem still have the same constrains with regular sudoku problem. So we could only change the variable of the constraints (the list of unit). Our original constraint propagation will adapt to this change without modification.

This project requires Python 3.

We recommend students install Anaconda, a pre-packaged Python distribution that contains all of the necessary libraries and software for this project. Please try using the environment we provided in the Anaconda lesson of the Nanodegree.

Optionally, you can also install pygame if you want to see your visualization. If you've followed our instructions for setting up our conda environment, you should be all set.

If not, please see how to download pygame here.

• solutions.py - You'll fill this in as part of your solution.
• solution_test.py - Do not modify this. You can test your solution by running python solution_test.py.
• PySudoku.py - Do not modify this. This is code for visualizing your solution.
• visualize.py - Do not modify this. This is code for visualizing your solution.

To visualize your solution, please only assign values to the values_dict using the assign_values function provided in solution.py

The data consists of a text file of diagonal sudokus for you to solve.