获取所有加起来为数字的数字

这是解决此问题的一种方法：

def sum_to_n(n, size, limit=None):    """Produce all lists of `size` positive integers in decreasing order    that add up to `n`."""    if size == 1:        yield [n]        return    if limit is None:        limit = n    start = (n + size - 1) // size    stop = min(limit, n - size + 1) + 1    for i in range(start, stop):        for tail in sum_to_n(n - i, size - 1, i): yield [i] + tail

您可以像这样使用它。

for partition in sum_to_n(6, 3):    print partition[2, 2, 2][3, 2, 1][4, 1, 1]