ch11_r01.py 文件源码

def binom(n: int, k: int) -> int:
    '''Computes the binomial coefficient.
    This shows how many combinations of
    *n* things taken in groups of size *k*.

    :param n: size of the universe
    :param k: size of each subset

    :returns: the number of combinations

    >>> binom(52, 5)
    2598960
    >>> binom(52, 0)
    1
    >>> binom(52, 52)
    1
    '''
    return factorial(n) // (factorial(k) * factorial(n-k))