Python 阶乘详解

#!/usr/bin/python3
"""Python2，3都可以"""
def factorial(n):#主体函数
    if n == 1:
        return 1
    return n * factorial(n-1)
res = input("请输入n:")
print(factorial(res))

>>> factorial(1000)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<stdin>", line 4, in factorial
  File "<stdin>", line 4, in factorial
  File "<stdin>", line 4, in factorial
  [Previous line repeated 995 more times]
  File "<stdin>", line 2, in factorial
RecursionError: maximum recursion depth exceeded in comparison

#!/usr/bin/python
li = []
def factorial(n):
    global li
    result = 1
    for i in range(n):
        li.append(i+1)
    for j in li:
        result = result * j
    return result
print(factorial(int(input("请输入n:"))))

import math
a = input("N:")
fac = math.factorial(a)
print(fac)

#中文变量名是合法的!
#中文变量名是合法的!!
#中文变量名是合法的!!!
数 = input("数:")
a = 1
for i in range(1,数+1):
    a = a * i
print(a)