37 lines
838 B
Python
37 lines
838 B
Python
import math
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def is_square(apositiveint):
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"""From: https://stackoverflow.com/a/2489519"""
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x = apositiveint // 2
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seen = set([x])
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while x * x != apositiveint:
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x = (x + (apositiveint // x)) // 2
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if x in seen:
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return False
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seen.add(x)
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return True
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def canditates(current_value, depth):
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if depth <= 0:
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yield current_value
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else:
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d = 10**depth
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for i in range(10):
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for new_value in canditates(current_value - i * d, depth - 2):
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yield new_value
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def euler_206():
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c = 1929394959697989990
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for i, c in enumerate(canditates(c, 17)):
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if is_square(c):
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return int(math.sqrt(c))
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if __name__ == "__main__":
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solution = euler_206()
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print("e206.py: " + str(solution))
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assert solution == 1389019170
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