增加for循环中的计数器

Question

我有一个看起来像这样的scala代码

object Main {
  def countChangeIter(money: Int, coins: List[Int], counter: Int): Int=

    if (money == 0)  1
    else if (money < 0)  0
    else {
      for (i <- coins.indices) {
      counter = counter + countChangeIter(money - coins(i), coins.drop(i), 0)


  }

    return counter
}


  def countChange(money: Int, coins: List[Int]): Int = countChangeIter(money, coins, 0)


}

问题在于counter = counter...声明。如何通过旧计数器和countChangeIter返回的总和来实现计数器的变化？

非常感谢 C14

Answer 1

您可以这样做：

 object Main {
      def countChangeIter(money: Int, coins: List[Int], counter: Int): Int=

        if (money == 0)  1
        else if (money < 0)  0
        else {
          var myCounter = counter
          for (i <- coins.indices) {
          myCounter = myCounter + countChangeIter(money - coins(i), coins.drop(i), 0)


      }

        return myCounter
    }


      def countChange(money: Int, coins: List[Int]): Int = countChangeIter(money, coins, 0)


    }

请记住，如果您需要在函数式编程设置中执行此操作，那么代码的结构可能有问题。