Stack-overflow in scala recursive change coin function

Question

Looking at the resources that the scala course from coursera offers I found an algorithm which should work ( the logic should work ) however when implemented in scala it returns a stack-overflow. I think I know what a stack is as I have played in C for a bit but I don't understand how the following function can use up so much memory:

      def countChange(money: Int, coins: List[Int]): Int = {


    def cc(amount: Int, list: List[Int]): Int = {
      if (amount == 0) 1
      if (amount < 0 || list.isEmpty) 0

      return cc(amount - list.head, list) + cc(amount, list.tail)

    }

    cc(money, coins)






  }

Here is the error:

Exception in thread "main" java.lang.StackOverflowError
at java.lang.Integer.valueOf(Unknown Source)
at scala.runtime.BoxesRunTime.boxToInteger(BoxesRunTime.java:70)
at recfun.Main$.cc$1(Main.scala:78)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)
at recfun.Main$.cc$1(Main.scala:80)

Here is the call to the function:

 println ("" + countChange(10,List(2,3,5)))

Answer 1

Wrong return behavior (mix expressions and statements)

Without return keyword:

def countChange(money: Int, coins: List[Int]): Int = {
  def cc(amount: Int, list: List[Int]): Int = {
    if (amount == 0) 1
    else if (amount < 0 || list.isEmpty) 0
    else cc(amount - list.head, list) + cc(amount, list.tail)
  }
  cc(money, coins)
}   

Or with return keyword:

def countChange1(money: Int, coins: List[Int]): Int = {
  def cc(amount: Int, list: List[Int]): Int = {
    if (amount == 0) return 1
    if (amount < 0 || list.isEmpty) return 0
    return cc(amount - list.head, list) + cc(amount, list.tail)
  }
  cc(money, coins)
}