问Euler # 21项目友好数字Python

EN

from time import time


def get_divisors(n):
    """Yields divisors of n."""
    divisor = 2
    while divisor * divisor <= n:
        if n % divisor == 0 and n // divisor != divisor:
            yield divisor
            if n // divisor != divisor:
                yield n // divisor
        divisor += 1
    yield 1


def get_sum_amicable(n, divs={2:1}):
    """Yields amicables below n."""
    for number1 in range(n):
        for number2 in range(number1):
            try:
                if divs[number2] == number1 and divs[number1] == number2:
                    yield number1
                    yield number2
            except KeyError:
                divs[number1] = sum(get_divisors(number1))
                divs[number2] = sum(get_divisors(number2))
                if divs[number2] == number1 and divs[number1] == number2:
                    yield number1
                    yield number2


if __name__ == '__main__':
    start = time()
    print(sum(get_sum_amicable(10000)))
    print(f'Time: {time() - start} seconds.')