sudoku-solver/square.py

"""This module contains the Square class."""


class Square:
    """A Square object represents a square on the board.

    The square's values will consist of a set of possible values for that
    square.
    The grid_id attribute identifies in which 9x9 grid the square belongs to.
    """

    def __init__(self, line, column, values):
        self.line = line
        self.column = column
        self.grid_id = self.compute_grid()
        self.coordinates = (self.line, self.column)
        self.values = values

    def compute_grid(self):
        """Given the coordinates, determine which grid the Square belongs to.

        The grids are numbered from 0 to 8, in the following configuration:
            0 1 2
            3 4 5
            6 7 8
        """

        grids = [
            (0, 0),  # grid 0
            (0, 1),  # grid 1
            (0, 2),  # grid 2
            (1, 0),  # grid 3
            (1, 1),  # grid 4
            (1, 2),  # grid 5
            (2, 0),  # grid 6
            (2, 1),  # grid 7
            (2, 2),  # grid 8
        ]

        grid_coordinates = (self.line // 3, self.column // 3)

        grid_number = 0
        while grids[grid_number] != grid_coordinates:
            grid_number += 1

            if grid_number == 9:
                return None

        return grid_number