38 lines
849 B
Python
38 lines
849 B
Python
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import math
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from itertools import permutations
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def first_n_digits(num, n):
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# https://stackoverflow.com/questions/41271299/how-can-i-get-the-first-two-digits-of-a-number
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p = int(math.log(num, 10)) - n + 1
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if p < 0:
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return num
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return num // 10 ** (int(math.log(num, 10)) - n + 1)
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def is_end_pandigital(n, ps):
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return (n % 10**9) in ps
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def is_start_pandigital(n, ps):
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start = first_n_digits(n, 9)
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return start in ps
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def euler_104():
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a, b = 1, 1
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ps = set([int("".join(map(str, p))) for p in permutations(range(1, 10))])
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k = 3
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while True:
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a, b = b, a + b
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if is_end_pandigital(b, ps) and is_start_pandigital(b, ps):
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return k
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k += 1
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if __name__ == "__main__":
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solution = euler_104()
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print("e104.py: " + str(solution))
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assert(solution == 329468)
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