你如何在 python 中为阶乘创建一个函数，该阶乘是使用递归的所有小于或等于 n 的正偶数整数的乘积

Question

def factorial(n):

if n == 0:

   return 1

else: 

   return n * factorial(n-2)

I can not seem to be able to figure this problem out. I can find the even integers for even factorials, but I can not seem to figure out how to find even integers for odd factorials at the same time. I've been at it for days now. I am extremely new to python, so any help would be very appreciative. Thanks!

Answer 1

This should work!

def factorial(n):
    if n % 2 != 0:
        n -= 1
    return 1 if (n < 1) else n * factorial(n-2)
    
print(factorial(6))
print(factorial(7))

The output will be:

48
48

Equals for n = 6 or n = 7 (even and odd numbers) as you can see

Answer 2

factorial = lambda x: functools.reduce(lambda x, y: x*y, range(2, x+1, 2))

使用内部方法functools.reduce防止最大递归深度