68 lines
1.3 KiB
Python
68 lines
1.3 KiB
Python
"""
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145 is a curious number, as 1! + 4! + 5! = 1 + 24 + 120 = 145.
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Find the sum of all numbers which are equal to the sum of the factorial of their digits.
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Note: As 1!=1 and 2!=2 are not sums they are not included.
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"""
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import time
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from functools import lru_cache
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def timer(func):
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def wrapper(*args, **kwargs):
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start_time = time.time()
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result = func(*args, **kwargs)
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end_time = time.time()
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print(f"{func.__name__} time: {end_time - start_time:.6f} seconds")
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return result
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return wrapper
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@lru_cache(maxsize=None)
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def factorial(n: int) -> int:
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if n == 0:
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return 1
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elif n == 1:
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return 1
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elif n == 2:
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return 2
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elif n == 3:
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return 6
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elif n == 4:
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return 24
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elif n == 5:
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return 120
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elif n == 6:
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return 720
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elif n == 7:
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return 5040
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elif n == 8:
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return 40320
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elif n == 9:
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return 362880
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elif n == 10:
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return 3628800
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else:
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return n * factorial(n - 1)
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def sum_digits(n: int) -> int:
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tmp = str(n)
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return sum(factorial(int(digit)) for digit in tmp)
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@timer
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def main() -> None:
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res = list()
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for i in range(12, 9999999):
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if sum_digits(i) == i:
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res.append(i)
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print(sum(res))
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if __name__ == "__main__":
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main()
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