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* Rename all Project Euler directories: Reason: The change was done to maintain consistency throughout the directory and to keep all directories in sorted order. Due to the above change, some config files had to be modified: 'problem_22` -> `problem_022` * Update scripts to pad zeroes in PE directories
64 lines
2.1 KiB
Python
64 lines
2.1 KiB
Python
"""
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Number letter counts
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Problem 17: https://projecteuler.net/problem=17
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If the numbers 1 to 5 are written out in words: one, two, three, four, five,
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then there are 3 + 3 + 5 + 4 + 4 = 19 letters used in total.
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If all the numbers from 1 to 1000 (one thousand) inclusive were written out in
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words, how many letters would be used?
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NOTE: Do not count spaces or hyphens. For example, 342 (three hundred and
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forty-two) contains 23 letters and 115 (one hundred and fifteen) contains 20
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letters. The use of "and" when writing out numbers is in compliance withBritish
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usage.
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"""
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def solution(n: int = 1000) -> int:
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"""Returns the number of letters used to write all numbers from 1 to n.
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where n is lower or equals to 1000.
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>>> solution(1000)
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21124
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>>> solution(5)
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19
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"""
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# number of letters in zero, one, two, ..., nineteen (0 for zero since it's
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# never said aloud)
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ones_counts = [0, 3, 3, 5, 4, 4, 3, 5, 5, 4, 3, 6, 6, 8, 8, 7, 7, 9, 8, 8]
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# number of letters in twenty, thirty, ..., ninety (0 for numbers less than
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# 20 due to inconsistency in teens)
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tens_counts = [0, 0, 6, 6, 5, 5, 5, 7, 6, 6]
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count = 0
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for i in range(1, n + 1):
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if i < 1000:
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if i >= 100:
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# add number of letters for "n hundred"
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count += ones_counts[i // 100] + 7
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if i % 100 != 0:
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# add number of letters for "and" if number is not multiple
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# of 100
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count += 3
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if 0 < i % 100 < 20:
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# add number of letters for one, two, three, ..., nineteen
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# (could be combined with below if not for inconsistency in
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# teens)
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count += ones_counts[i % 100]
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else:
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# add number of letters for twenty, twenty one, ..., ninety
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# nine
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count += ones_counts[i % 10]
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count += tens_counts[(i % 100 - i % 10) // 10]
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else:
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count += ones_counts[i // 1000] + 8
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return count
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if __name__ == "__main__":
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print(solution(int(input().strip())))
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