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https://github.com/kennethreitz/dive-into-python3.git
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Mark Pilgrim
58 lines
2.4 KiB
Python
58 lines
2.4 KiB
Python
import re
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import itertools
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def solve(puzzle):
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'''Find solutions to alphametic equations.
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>>> solve('SEND + MORE == MONEY')
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9567 + 1085 == 10652
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'''
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words = re.findall('[A-Z]+', puzzle)
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unique_characters = set(''.join(words))
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assert len(unique_characters) <= 10
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first_letters = set(word[0] for word in words)
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n = len(first_letters)
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sorted_characters = ''.join(first_letters) + \
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''.join(unique_characters - first_letters)
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characters = tuple(map(ord, sorted_characters))
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digits = tuple(map(ord, '0123456789'))
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zero = digits[0]
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for guess in itertools.permutations(digits, len(characters)):
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if zero not in guess[:n]:
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equation = puzzle.translate(dict(zip(characters, guess)))
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if eval(equation):
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return equation
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if __name__ == '__main__':
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import sys
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for puzzle in sys.argv[1:]:
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print(puzzle)
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for solution in solve(puzzle):
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print(solution)
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# Copyright (c) 2009, Raymond Hettinger, All rights reserved.
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# Ported to Python 3 and modified by Mark Pilgrim
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# original: http://code.activestate.com/recipes/576615/
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#
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# Redistribution and use in source and binary forms, with or without modification,
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# are permitted provided that the following conditions are met:
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#
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# * Redistributions of source code must retain the above copyright notice,
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# this list of conditions and the following disclaimer.
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# * Redistributions in binary form must reproduce the above copyright notice,
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# this list of conditions and the following disclaimer in the documentation
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# and/or other materials provided with the distribution.
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#
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# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 'AS IS'
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# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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# POSSIBILITY OF SUCH DAMAGE.
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