Q: How do we use constraint propagation to solve the naked twins problem?
A: If two boxes in the same unit have the same two value candidates and only those two (naked twins), then no other box in the same unit could be one of the two values. Therefore we can emliminate those two values from all boxes except the naked twins. This therefore is a strategy which can help in situation where all other strategies fail or would take much iterations.
Q: How do we use constraint propagation to solve the diagonal sudoku problem?
A: In this case the two diagonal units also have to have alle values from one to nine as all other units. We can use all existing strategies (elimination, only choice...) if we just add the diagonals to the units and peers. Implementing those constraints leads to more exclusions from the known boxes for all strategies and therefore to faster convergence.
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.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_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.