Factorial

In mathematics, the factorial of a non-negative integer n, denoted by n!, is the product of all positive integers less than or equal to n. For example: 5! = 5 * 4 * 3 * 2 * 1 = 120. By convention the value of 0! is 1.

Write a function to calculate factorial for a given input. If input is below 0 or above 12 throw an exception of type ArgumentOutOfRangeException (C#) or IllegalArgumentException (Java) or RangeException (PHP) or throw a RangeError (JavaScript) or ValueError (Python) or return -1 (C).

More details about factorial can be found here.

 

Solution:

import math

def factorial(n):
    if n < 0 or n > 12:
        raise ValueError
    return math.prod(list(range(1, n+1))) or 1

math.prod multiplies the elements of an array.