一个数的阶乘的Python程序

非负整数的阶乘，是所有小于或等于 n 的整数的乘积。例如，6 的阶乘是 6*5*4*3*2*1，即 720。

1.递归：

python3

# Python 3 program to find
# factorial of given number
def factorial(n):
     
    # single line to find factorial
    return 1 if (n==1 or n==0) else n * factorial(n - 1);
 
# Driver Code
num = 5;
print("Factorial of",num,"is",
factorial(num))
 
# This code is contributed by Smitha Dinesh Semwal

输出：

Factorial of 5 is 120

2. 迭代：

蟒蛇3

# Python 3 program to find 
# factorial of given number
def factorial(n):
    if n < 0:
        return 0
    elif n == 0 or n == 1:
        return 1
    else:
        fact = 1
        while(n > 1):
            fact *= n
            n -= 1
        return fact
 
# Driver Code
num = 5;
print("Factorial of",num,"is",
factorial(num))
 
# This code is contributed by Dharmik Thakkar

输出：

Factorial of 5 is 120

3.一条线解决方案（使用三元运算符）：

Python3

# Python 3 program to find
# factorial of given number
 
def factorial(n):
 
    # single line to find factorial
    return 1 if (n==1 or n==0) else n * factorial(n - 1)
 
 
# Driver Code
num = 5
print ("Factorial of",num,"is",
      factorial(num))
 
# This code is contributed
# by Smitha Dinesh Semwal.

输出：

Factorial of 5 is 120

有关更多详细信息，请参阅有关数字阶乘的完整文章！

4.通过使用内置函数：

Python3

# Python 3 program to find
# factorial of given number
import math
 
def factorial(n):
    return(math.factorial(n))
 
 
# Driver Code
num = 5
print("Factorial of", num, "is",
      factorial(num))
 
# This code is contributed by Ashutosh Pandit

输出：

Factorial of 5 is 120