How to find factorial in python

Python factorial method: 1. Use an ordinary for loop; 2. Use the [reduce()] function, the code is [num = reduce(lambda x,y:x*y,range(1,7 ))]; 3. Use the [factorial()] function; 4. Call the method recursively.

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Python factorial method:

The first method : Ordinary for loop

a = int(input('please inputer a integer:'))
num = 1
if a < 0:
    print(&#39;负数没有阶乘！&#39;)
elif a == 0:
    print(&#39;0的阶乘为1！&#39;)
else :
    for i in range(1,a + 1):
        num *= i
    print(num)

The second type: reduce() function

#从functools中调用reduce()函数
from functools import reduce
#使用lambda，匿名函数，迭代
num = reduce(lambda x,y:x*y,range(1,7))
print(num)

The third type: factorial() function

import math
value = math.factorial(6)
print(value)

The fourth type: recursive call

def num(n):
    if n == 0:
        return 1
    else:
        return n * num(n - 1)
print(num(6)

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