Name: Dario Arcos-Diaz

Q: How do we use constraint propagation to solve the naked twins problem?
A: For each unit of the sudoku we identify the naked twins by finding those boxes that have the same two-digit value in that unit. Then, we can iterate through the rest of (non-twin) boxes of the unit and remove the two locked digits. This way we use an additional constraint to solve the puzzle more quickly.

Q: How do we use constraint propagation to solve the diagonal sudoku problem?
A: In a normal sudoku we have row units, column units, and square units. In a diagonal sudoku we have two additional units: the "diagonal units"

diag_units = [['A1', 'B2', 'C3', 'D4', 'E5', 'F6', 'G7', 'H8', 'I9'], 
['A9', 'B8', 'C7', 'D6', 'E5', 'F4', 'G3', 'H2', 'I1']]

Once we define them and add them to the full unit list, all other functions that iterate through units will automatically do so through the additional diagonal units.

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.