Q: How do we use constraint propagation to solve the naked twins problem?
A: After identifying all the naked twins in a unit of the board, we know that the two naked twin values cannot appear anywhere else in that unit. So we propagate that constraint to the other boxes in that unit by eliminating those values from the other boxes.
Q: How do we use constraint propagation to solve the diagonal sudoku problem?
A: The diagonal sudoku problem as two additional constraints, namely that each digit needs to appear along the diagonals of the grid exactly once. After adding these two constraints, we apply constraint propagation the same way that we did for square, row, and column units. We use elimination and only choice iteratively to remove possibilities that do not satisfy our constraints.
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 runningpython 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.