python中阶乘的递归和迭代实现

使用递归实现阶乘：

def fac1(n):
    if n == 1:
        result = 1
    else:
        result = n * fac1(n-1)
    return result

使用迭代实现阶乘：

def fac2(n):
    result = 1
    for i in [m + 1 for m in range(n)]:
        result = result * i
    return result

def fac3(n):
    result = 1
    for i in range(1, n+1):
        result *= i
    return result