41 lines
811 B
Python
41 lines
811 B
Python
'''ISBN13 check digit'''
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from itertools import cycle
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# isISBN13 :: String -> Bool
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def isISBN13(s):
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'''True if s is a valid ISBN13 string
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'''
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digits = [int(c) for c in s if c.isdigit()]
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return 13 == len(digits) and (
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0 == sum(map(
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lambda f, x: f(x),
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cycle([
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lambda x: x,
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lambda x: 3 * x
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]),
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digits
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)) % 10
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)
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# ------------------------- TEST -------------------------
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# main :: IO ()
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def main():
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'''Test strings for ISBN-13 validity.'''
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print('\n'.join(
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repr((s, isISBN13(s))) for s
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in ["978-0596528126",
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"978-0596528120",
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"978-1788399081",
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"978-1788399083"
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]
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))
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# MAIN ---
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if __name__ == '__main__':
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main()
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