Exercise 21: Implement the factorial function

gistfile1.txt

Write a factorial method which takes as its input a non-negative integer and calculates the factorial of that number.

The factorial of a number is the product of all integers from 1 up to that number. For example:

factorial(5) == 5 * 4 * 3 * 2 * 1 == 120
The factorial of 0 is defined to be 1.

------------CODE-------------



def factorial(n)
  if n == 0
    return 1
  end#if
  
  counter = 1
  array = []
  unless counter > n do
    array.push counter
  end#unless
  
  factorial = 0
  array.each do |value|
    if factorial == 0
      factorial = value
    else
      factorial = factorial * value
    end#else, if
  end#each
    
    return factorial
  
end#def