Q: How do we use constraint propagation to solve the naked twins problem?
A: We need to check every unit to find if they have one or more pairs of naked twins. If we find any, this means we can remove the two values that appear on them, from the other boxes of the unit, because they can only be contained in the naked twins. This can help to get one step closer to the solution.
Q: How do we use constraint propagation to solve the diagonal sudoku problem?
A: We use the two diagonals of the puzzle as another pair of units, that have the same restrictions the other units have. This is a new constraint that we need to satisfy. We can use it when we apply any of the techniques we are using (elimination, only_choice, naked_twins) because these strategies use the constraints of the units to get closer to a global solution.
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.
solution.py- You'll fill this in as part of your solution.test_solution.py- Do not modify this. You can test your solution by runningpython -m unittest.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_value function provided in solution.py
Before submitting your solution to a reviewer, you are required to submit your project to Udacity's Project Assistant, which will provide some initial feedback.
The setup is simple. If you have not installed the client tool already, then you may do so with the command pip install udacity-pa.
To submit your code to the project assistant, run udacity submit from within the top-level directory of this project. You will be prompted for a username and password. If you login using google or facebook, visit this link for alternate login instructions.
This process will create a zipfile in your top-level directory named sudoku-.zip. This is the file that you should submit to the Udacity reviews system.