Q: How do we use constraint propagation to solve the naked twins problem?
A: *
Following order of constraints were implemented for solving the naked twins problem:
1. Twins could only happen with unsolved two-digit elements in the grid. Following steps were carried out on each two-digit box found in the grid.
2. Row, column, square and diagonal (if applicable) units containing a two-digit element needed to be searched for existence of twins.
3. For a twin detected in above step, digits were removed from other unsolved elements in row, column, square and diagonal units.
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Q: How do we use constraint propagation to solve the diagonal sudoku problem?
A: *
Diagonal sudoku needed additional constraint of two diagonals having numbers 1 through 9 exactly once. Following order of steps were followed:
1. In addition to row, column and square units, diagonal units were defined to apply the diagonal constraint.
2. Units and peers for each element in the grid were modified to include diagonal units for applying elemination, only_choice and naked_twin constrains.
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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_values 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](https://project-assistant.udacity.com/auth_tokens/jwt_login 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.