165 lines
4.3 KiB
Python
165 lines
4.3 KiB
Python
#!/usr/bin/python3
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# -*- coding: utf-8 -*-
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"""
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:mod:`sudoku_solver` module
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:author: `Éric W`
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:date: 2016, october
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:Provides:
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* a function `solve` to solve sudoku grids
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:Example: with the following sudoku grid
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.. code-block:: text
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+-------+-------+-------+
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| 9 . 6 | . 2 8 | . . 3 |
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| . 4 . | 5 . . | . . 1 |
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| . 8 . | 9 . . | . 4 . |
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+-------+-------+-------+
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| 6 . . | . . . | . 7 . |
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| . . 8 | 2 . 6 | 9 . . |
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| . 3 . | . . . | . . 5 |
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+-------+-------+-------+
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| . 5 . | . . 3 | . 6 . |
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| 1 . . | . . 2 | . 8 . |
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| 2 . . | 8 7 . | 5 . . |
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+-------+-------+-------+
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and second with the grid
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.. code-block:: text
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+-------+-------+-------+
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| 9 . 6 | . 2 8 | . . 3 |
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| . 4 . | 5 . . | . . 1 |
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| . 8 . | 9 . . | . 4 . |
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+-------+-------+-------+
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| 6 . . | . . . | . 7 . |
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| . . 8 | 2 . 6 | 9 . . |
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| . 3 . | . . . | . . 5 |
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+-------+-------+-------+
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| . 5 . | . . 3 | . 6 . |
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| 1 . . | . . 2 | . 8 . |
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| 2 . . | 8 7 . | . . . |
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+-------+-------+-------+
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>>> from sudoku_grid import SudokuGrid
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>>> strgrid = '906028003040500001080900040600000070008206900030000005050003060100002080200870500'
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>>> grid = SudokuGrid(strgrid)
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>>> solved_grid = solve(grid)
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>>> len(solved_grid)
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1
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>>> solved_grid[0].pretty_print()
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+-------+-------+-------+
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| 9 1 6 | 4 2 8 | 7 5 3 |
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| 3 4 2 | 5 6 7 | 8 9 1 |
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| 7 8 5 | 9 3 1 | 2 4 6 |
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+-------+-------+-------+
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| 6 2 9 | 3 4 5 | 1 7 8 |
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| 5 7 8 | 2 1 6 | 9 3 4 |
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| 4 3 1 | 7 8 9 | 6 2 5 |
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+-------+-------+-------+
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| 8 5 7 | 1 9 3 | 4 6 2 |
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| 1 9 4 | 6 5 2 | 3 8 7 |
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| 2 6 3 | 8 7 4 | 5 1 9 |
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+-------+-------+-------+
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"""
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import time
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from sudoku_grid import SudokuGrid, EMPTY_SYMBOL
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def __possible_values(s):
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"""
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"""
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return "".join(c for c in '123456789' if c not in s)
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def __grid_exam(grid):
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"""
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"""
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ROWS = [grid.get_row(r) for r in range(9)]
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COLS = [grid.get_col(c) for c in range(9)]
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SQUARES = [grid.get_square(3*r, 3*c) for r in range(3) for c in range(3)]
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poss_min, coord_min = '0123456789', (-1, -1)
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for r in range(9):
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for c in range(9):
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if grid.is_empty_cell(r, c):
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poss = __possible_values(ROWS[r] + COLS[c] + SQUARES[3 * (r // 3) + (c // 3)])
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if len(poss) < len(poss_min):
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poss_min = poss
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coord_min = (r, c)
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return poss_min, coord_min
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def __is_solved(grid):
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"""
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:param grid: a Sudoku grid
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:typr grid: sudoku_grid.grid
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:return: `True` if the grid is solved, `False` otherwise
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:rtype: bool
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:UC: none
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"""
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return not any(grid.is_empty_cell(row, col) for row in range(9) for col in range(9))
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def solve(grid, out_channel=None, node=None):
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"""
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:param grid: a Sudoku grid to solve
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:type grid: SudokuGrid
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:return: list of solutions (solved grids)
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:rtype: list
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:UC: none
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"""
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if __is_solved(grid):
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if not out_channel is None:
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out_channel.write('\t"{:s}"[shape=hexagon, fillcolor="#00FF00"];\n'.format(node))
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return [grid.copy()]
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else:
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maybe, (i, j) = __grid_exam(grid)
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res = []
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for c in maybe:
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if not out_channel is None:
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label = str((c, i, j))
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next_node = node + '{:s}{:d}{:d}'.format(c, i, j)
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out_channel.write('\t"{:s}"[label="{:s}"];\n'.format(next_node, label))
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out_channel.write('\t"{:s}" -> "{:s}";\n'.format(node, next_node))
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else:
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next_node = None
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grid[i, j] = c
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res += solve(grid, out_channel, next_node)
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grid[i, j] = EMPTY_SYMBOL
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return res
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def solve_one(grid, pause=0):
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"""
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:param grid: a Sudoku grid to solve
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:type grid: sudoku_grid.grid
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:return: a solution of grid
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:rtype: sudoku_grid.grid
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:UC: none
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"""
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time.sleep(pause)
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print("\x1b[2J", end='')
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grid.pretty_print()
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if __is_solved(grid):
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return [grid]
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else:
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maybe, (i, j) = __grid_exam(grid)
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res = None
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for c in maybe:
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grid[i, j] = c
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res = solve_one(grid, pause)
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if not res is None:
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return res
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grid[i, j] = EMPTY_SYMBOL
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return res
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if __name__ == '__main__':
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import doctest
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doctest.testmod ()
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