要求

设计一个收银程序 checkCashRegister() ，其把购买价格(price)作为第一个参数 , 付款金额 (cash)作为第二个参数, 和收银机中零钱 (cid) 作为第三个参数.
cid 是一个二维数组，存着当前可用的找零.
当收银机中的钱不够找零时返回字符串 "Insufficient Funds". 如果正好则返回字符串 "Closed".否则, 返回应找回的零钱列表,且由大到小存在二维数组中.

解答

function checkCashRegister(price, cash, cid) {
  var change;
  var base=100;
  change=(cash-price)*base;
  var getTotalMoney=function(arr){
    var s=arr.reduce(function(preV,currV,currIndex,array){
      return preV+currV[1];
    },0);
    return s*base;
  };
  var objCash={
   "PENNY": 1,
   "NICKEL": 5,
   "DIME": 10,
   "QUARTER": 25,
   "ONE": 100,
   "FIVE": 500,
   "TEN": 1000,
   "TWENTY": 2000,
   "ONE HUNDRED": 10000
  };
  var totalMoney=getTotalMoney(cid);
  if(totalMoney<change) 
    return "Insufficient Funds";
  var changearr=[];//找钱列表
  var currMoney=0;//当前面额  
  var currLast=0;//当前面值所剩余额
  var currTotal=0;//当前零钱可找总额
  for(i=cid.length-1;i>=0;i--){
    currMoney=objCash[cid[i][0]];
    currLast=cid[i][1]*base;
    if(currLast===0) continue;
    if(change>currMoney){
      if(change<currLast)
        currTotal=currMoney*Math.floor(change/currMoney);
      else
        currTotal=currLast;
      change-=currTotal;
      changearr.push([cid[i][0],currTotal/base]);
    }
  }
  if(change>0)//找不开
    return "Insufficient Funds";
  else if((change===0)&&((cash-price)*base==totalMoney))
    return "Closed";
  else
    return changearr;
}

// Example cash-in-drawer array:
// [["PENNY", 1.01],
// ["NICKEL", 2.05],
// ["DIME", 3.10],
// ["QUARTER", 4.25],
// ["ONE", 90.00],
// ["FIVE", 55.00],
// ["TEN", 20.00],
// ["TWENTY", 60.00],
// ["ONE HUNDRED", 100.00]]

checkCashRegister(19.50, 20.00, [["PENNY", 1.01], ["NICKEL", 2.05], ["DIME", 3.10], ["QUARTER", 4.25], ["ONE", 90.00], ["FIVE", 55.00], ["TEN", 20.00], ["TWENTY", 60.00], ["ONE HUNDRED", 100.00]]);