Factorial Tail Rec

factorialtailrec.scala

object factorial {
  println("Welcome to the Scala worksheet")       //> Welcome to the Scala worksheet
  
  def factorial(n : Int) : Int =  {
  	if (n == 0) 1 else n * factorial(n-1)
  }                                               //> factorial: (n: Int)Int
  
  def factorial2(n : Int) : Int = {
  	
  	def innerFact(n : Int, count : Int, acum : Int) : Int = {
  		if (n + 1 == count) acum
  		else innerFact(n, count + 1, acum * count)
  		
  	}
  	
  	innerFact(n, 1, 1);
  	
  }                                               //> factorial2: (n: Int)Int
  
  factorial(4)                                    //> res0: Int = 24
  factorial(5)                                    //> res1: Int = 120
  factorial2(4)                                   //> res2: Int = 24
  factorial2(5)                                   //> res3: Int = 120
}