60 lines
1.7 KiB
Python
60 lines
1.7 KiB
Python
def get_four_digit_numbers(function):
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r = []
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n = 1
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f = function
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while f(n) < 10000:
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if f(n) > 999:
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r.append(f(n))
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n += 1
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return r
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def search_solution(aggregator, polygonals):
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if not polygonals:
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if is_cyclic(aggregator[-1], aggregator[0]):
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return aggregator
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else:
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return []
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if not aggregator:
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for polygonal in polygonals:
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for number in polygonal:
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aggregator.append(number)
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s = search_solution(
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aggregator, [p for p in polygonals if p != polygonal])
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if s:
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return s
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aggregator.pop()
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for polygonal in polygonals:
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for number in polygonal:
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if is_cyclic(aggregator[-1], number) and number not in aggregator:
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aggregator.append(number)
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s = search_solution(
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aggregator, [p for p in polygonals if p != polygonal])
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if s:
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return s
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aggregator.pop()
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return []
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def is_cyclic(a, b):
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return str(a)[-2:] == str(b)[:2]
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def euler_061():
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triangles = get_four_digit_numbers(lambda n: n * (n + 1) // 2)
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squares = get_four_digit_numbers(lambda n: n**2)
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pentas = get_four_digit_numbers(lambda n: n * (3 * n - 1) // 2)
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hexas = get_four_digit_numbers(lambda n: n * (2 * n - 1))
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heptas = get_four_digit_numbers(lambda n: n * (5 * n - 3) // 2)
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octas = get_four_digit_numbers(lambda n: n * (3 * n - 2))
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s = search_solution([], [triangles, squares, pentas, hexas, heptas, octas])
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s = sum(s)
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return s
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if __name__ == "__main__":
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print("e061.py: " + str(euler_061()))
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assert(euler_061() == 28684)
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