FreeCodeCamp---advanced Algorithm Scripting解法

Exact Change

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.

 function checkCashRegister(price, cash, cid) {
   var arr=[];  //应找回的零钱列表
   var cashPrice=[];  //一种钱代表的金额
   var cashName=[];  //钱的名字
   var cashItemSum=[];  //一种钱的总数
   var change=Math.round((cash-price)*100)/100;   //要找回的零钱
   var sumCash=0;
   cid.forEach(function(item,index,array){
     if(item[1]>0){
       cashName.push(item[0]);
       cashItemSum.push(item[1]);
       sumCash += item[1];
     }
   });

   cashPrice=cashName.map(function(item,index,array){
     switch (item){
       case "PENNY":
         return 0.01;
       case "NICKEL":
         return 0.05;
       case "DIME":
         return 0.1;
       case "QUARTER":
         return 0.25;
       case "ONE":
         return 1;
       case "FIVE":
         return 5;
       case "TEN":
         return 10;
       case "TWENTY":
         return 20;
       case "ONE HUNDRED":
         return 100;
     }
   });

   sumCash=Math.round(sumCash*100)/100; //对sumCash保留两位小数

   switch (true){
     case change>sumCash:
       return "Insufficient Funds";
     case change === sumCash:
       return "Closed";
     default:
       approachChange(change);
       if(arr.length===0){
         return "Insufficient Funds";
       }else{
         return arr;
       }
   }

   function approachChange(change){
     var index=0;
     if(change>cashPrice[cashPrice.length-1]){
       index=cashPrice.length-1;
     }

     for(var i=0; i<cashPrice.length-1; i++){
       if(cashPrice[i]<=change && change<cashPrice[i+1] && cashItemSum[i]!==0){
          index=i;
       }
     }

     var itemNeedSum=Math.floor(change/cashPrice[index]) * cashPrice[index];
     var needMin=Math.min(itemNeedSum,cashItemSum[index]);
     var x=Math.round( (change-needMin)*100 )/100;

     if(x>0 && index===0){
       return;
     }

     arr.push([cashName[index], needMin]);      

     if(x===0){
       return;
     }else{
       cashPrice=cashPrice.slice(0,index);
       approachChange(x);
     }
   }

 }

 checkCashRegister(19.50, 20.00, [["PENNY", 0.01], ["NICKEL", 0], ["DIME", 0], ["QUARTER", 0], ["ONE", 1.00], ["FIVE", 0], ["TEN", 0], ["TWENTY", 0], ["ONE HUNDRED", 0]]);