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80 lines
1.8 KiB
Python
80 lines
1.8 KiB
Python
#!/usr/bin/python
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# vim:set fileencoding=utf-8:
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"""
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A backtracking Sudoku solver.
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"""
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from __future__ import division, print_function
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import numpy as np
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import time
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puzzle = [3, 7, 0, 0, 0, 4, 9, 5, 1,
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0, 0, 2, 5, 0, 0, 0, 0, 8,
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0, 0, 0, 0, 0, 0, 0, 0, 7,
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0, 0, 0, 0, 0, 3, 0, 2, 0,
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0, 1, 0, 0, 2, 0, 0, 4, 0,
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0, 5, 0, 9, 0, 0, 0, 0, 0,
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8, 0, 0, 0, 0, 0, 0, 0, 0,
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7, 0, 0, 0, 0, 5, 3, 0, 0,
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5, 9, 4, 6, 0, 0, 0, 7, 2]
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puzzle = np.array(puzzle).reshape(9, 9)
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visual = True
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def valid():
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rows = np.vsplit(puzzle, 9)
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cols = np.hsplit(puzzle, 9)
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grids = [grid for h in np.hsplit(puzzle, 3) for grid in np.vsplit(h, 3)]
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units = rows + cols + grids
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return all(np.max(np.bincount(unit[unit != 0])) == 1 for unit in units)
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def print_puzzle(clear=True):
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ANSI_CPL = "\033[%dF" # CPL = Cursor Previous Line
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if clear:
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print(ANSI_CPL % 10)
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for row in np.vsplit(puzzle, 9):
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for element in row[0]:
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if element != 0:
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print(element, end=' ')
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else:
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print('‧', end=' ')
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print()
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def set_next_number():
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position = find_first(puzzle == 0)
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for number in range(1, 10):
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puzzle[position] = number
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if valid():
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if visual:
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print_puzzle()
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time.sleep(0.005)
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if 0 not in puzzle:
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# Solved
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return True
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else:
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if set_next_number():
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return True
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# dead end ⇒ backtrack
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puzzle[position] = 0
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return False
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def find_first(condition):
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return tuple(p[0] for p in np.where(condition))
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print(__doc__)
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print_puzzle(clear=False)
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if set_next_number():
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print_puzzle()
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