递归函数未在另一个函数中调用的潜在问题

Question

我正在尝试构建一个收银机（FreeCodeCamp 中的一个算法项目）并且我已经创建了一个函数（giveChange()，一个递归函数）以在另一个单独的函数（checkCashRegister）中调用。

但是，函数没有被调用。在我的例子中，我希望函数 checkCashRegister 为 return 0。

查了下是for循环中"return"放错地方的问题还是作用域的问题。好像也没有。

function giveChange(diff, cid) {       
  for(let i = cid.length - 1; i > 0; i--) {
    if(cid[i-1][0] <= diff && diff <= cid[i][0]) {
      diff = diff - Math.min(cid[i-1][1], cid[i-1][0]*Math.ceil(((diff-cid[i-1][0])/cid[i-1][0])))
      if(diff !== 0) {
        giveChange(diff, cid)
      } else {
        return diff
      }
    }
  }
  return diff
}

function checkCashRegister(price, cash, cid) {
 
  let diff = cash - price
  cid[0][0] = 0.01
  cid[1][0] = 0.05
  cid[2][0] = 0.1
  cid[3][0] = 0.25
  cid[4][0] = 1
  cid[5][0] = 5
  cid[6][0] = 10
  cid[7][0] = 20
  cid[8][0] = 100

  giveChange(diff, cid)

  return diff
}

checkCashRegister(3.26, 100, [["PENNY", 1.01], ["NICKEL", 2.05], ["DIME", 3.1], ["QUARTER", 4.25], ["ONE", 90], ["FIVE", 55], ["TEN", 20], ["TWENTY", 60], ["ONE HUNDRED", 100]])

Answer 1

您在调用 givechange(diff, cid)、

之前缺少 return 关键字

注意：我已经更新了条件并使用三元来不重复 return 关键字

function giveChange(diff, cid) {
  for (let i = cid.length - 1; i > 0; i--) {
    if (cid[i - 1][0] <= diff && diff <= cid[i][0]) {
      diff = diff - Math.min(cid[i - 1][1], cid[i - 1][0] * Math.ceil(((diff - cid[i - 1][0]) / cid[i - 1][0])))
      return diff !== 0 ? giveChange(diff, cid) : diff
    }
  }
  console.log(diff)
  return diff
}

function checkCashRegister(price, cash, cid) {

  let diff = cash - price
  cid[0][0] = 0.01
  cid[1][0] = 0.05
  cid[2][0] = 0.1
  cid[3][0] = 0.25
  cid[4][0] = 1
  cid[5][0] = 5
  cid[6][0] = 10
  cid[7][0] = 20
  cid[8][0] = 100

  return giveChange(diff, cid)
}

checkCashRegister(3.26, 100, [
  ["PENNY", 1.01],
  ["NICKEL", 2.05],
  ["DIME", 3.1],
  ["QUARTER", 4.25],
  ["ONE", 90],
  ["FIVE", 55],
  ["TEN", 20],
  ["TWENTY", 60],
  ["ONE HUNDRED", 100]
])

递归函数未在另一个函数中调用的潜在问题

Potential issues for recursive function not being called in another function

javascript

function

recursion

return