/**
    * Exercise 3
    */
  def countChange(money: Int, coins: List[Int]): Int = {
    def iterator(money: Int, coins: List[Int], acc: Int = 0): Int = {
      if (!coins.isEmpty) {
        val rest = money - coins.head

        if (rest > 0) iterator(money, coins.tail, iterator(rest, coins, acc))
        else if (rest == 0) iterator(money, coins.tail, acc + 1)
        else iterator(money, coins.tail, acc)

      } else acc
    }

    iterator(money, coins)
  }