factorial.rb

# Implement an iterative version of the factorial function
def factorial_iterative(n)
  total = n

  until n == 1
   total *= n-1  #if n=2, total=2*n(1)! elseif n=3, total=3*n(2)!
   n -= 1
  end

  total
end

p factorial_iterative(1) == 1
p factorial_iterative(2) == 2
p factorial_iterative(3) == 6
p factorial_iterative(4) == 24
p factorial_recursive(9) == 362880

# Implement a recursive version of the factorial function
def factorial_recursive(n)
	return 1 if n==1
	n * factorial_recursive(n-1)  # if n==2, e.g 2*(2-1)!
end

p factorial_recursive(1) == 1
p factorial_recursive(2) == 2
p factorial_recursive(3) == 6
p factorial_recursive(4) == 24
pfactorial_recursive(9) == 362880