[FCC] Cash Register 计算找零

题目地址：

https://chinese.freecodecamp.org/learn/javascript-algorithms-and-data-structures/javascript-algorithms-and-data-structures-projects/cash-register

关键在于如何找零，从大面额开始尝试，如果最后 change 变为 0 找零成功。如果不转换为美分再计算要注意浮点数的误差。

function checkCashRegister(price, cash, cid) {

  const table = {

    "PENNY": 0.01,

    "NICKEL": 0.05,

    "DIME": 0.1,

    "QUARTER": 0.25,

    "ONE": 1,

    "FIVE": 5,

    "TEN": 10,

    "TWENTY": 20,

    "ONE HUNDRED": 100

  };

  // console.log(cid)

  let change = cash - price;

  // console.log(change)

  let status = "OPEN";

  // 寻找找零方案

  let res = [];

  for (let i = cid.length-1; i >= 0; i--) {

    let coin = [cid[i][0], 0];

    while (change >= table[coin[0]] && coin[1] < cid[i][1]) {

      change -= table[coin[0]];

      change = Math.round(change*100) /100;  // 精确到小数点后2位

      coin[1] += table[coin[0]];

      coin[1] = Math.round(coin[1] * 100) /100;

    }

    console.log(coin, change)

    if (coin[1] > 0) {

      res.push(coin);

    }

  }

  // console.log(res)

  if (change == 0) {

    let isClosed = false;

    if (res.reduce((total, value) => total + value[1], 0) == cid.reduce((total, it) => total+it[1], 0)) {

      isClosed = true;

    }

    if (isClosed) {

      status = "CLOSED";

      res = cid;

    }

  } else {

    status = "INSUFFICIENT_FUNDS"

    res.length = 0

  }

  return {status: status, change: res};

}

[FCC] Cash Register 计算找零的相关教程结束。