76 lines
1.7 KiB
Python
76 lines
1.7 KiB
Python
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CHAR_TO_INT = [
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('M', 1000),
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('CM', 900),
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('D', 500),
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('CD', 400),
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('C', 100),
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('XC', 90),
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('L', 50),
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('XL', 40),
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('X', 10),
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('IX', 9),
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('V', 5),
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('IV', 4),
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('I', 1),
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]
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def tests():
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assert(numeral_to_integer("XXXXIIIIIIIII") == 49)
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assert(numeral_to_integer("XLIIIIIIIII") == 49)
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assert(numeral_to_integer("XXXXVIIII") == 49)
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assert(numeral_to_integer("XLVIIII") == 49)
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assert(numeral_to_integer("XXXXIX") == 49)
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assert("XLIX" == integer_to_numeral(49))
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assert("MCMXXXVII" == integer_to_numeral(1937))
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def integer_to_numeral(integer):
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i = 0
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s = ''
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while integer > 0:
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char, value = CHAR_TO_INT[i]
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while integer >= value:
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s += char
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integer -= value
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i += 1
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assert(integer == 0)
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return s
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def numeral_to_integer(numeral):
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i, r = 0, 0
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while numeral and i < len(CHAR_TO_INT):
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char, value = CHAR_TO_INT[i]
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len_char = len(char)
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while len(numeral) >= len_char and numeral[:len_char] == char:
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r += value
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numeral = numeral[len_char:]
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i += 1
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assert(not numeral)
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return r
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def save_characters(numeral):
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initial_chars = len(numeral)
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i = numeral_to_integer(numeral)
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new_numeral = integer_to_numeral(i)
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new_chars = len(new_numeral)
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return initial_chars - new_chars
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def euler_089():
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tests()
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with open("../txt/e089.txt") as f:
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numerals = map(lambda l: l.strip(), f.readlines())
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return sum(map(save_characters, numerals))
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if __name__ == "__main__":
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solution = euler_089()
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print("e089.py: " + str(solution))
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assert(solution == 743)
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