Exercise 3: Counting Change

countChange.sc

package week1

object countChange {

  def countChange(money: Int, coins: List[Int]): Int = {
    if (money > 0 && !coins.isEmpty)
      countChange(money, coins.tail) + countChange(money - coins.head, coins)
    else if (money == 0) 1 else 0
  }                                               //> countChange: (money: Int, coins: List[Int])Int

  countChange(0, List(1,2)) == 0                  //> res0: Boolean = false
  countChange(0, List()) == 0                     //> res1: Boolean = false
  countChange(4, List()) == 0                     //> res2: Boolean = true
  countChange(4, List(1, 2)) == 3                 //> res3: Boolean = true
  countChange(300, List(5, 10, 20, 50, 100, 200, 500)) == 1022
                                                  //> res4: Boolean = true
  countChange(301, List(5, 10, 20, 50, 100, 200, 500)) == 0
                                                  //> res5: Boolean = true
  countChange(300, List(500, 5, 50, 100, 20, 200, 10)) == 1022
                                                  //> res6: Boolean = true

}