greedy.js

const CENTS = 100;

function toCents(amount) {
  return Math.ceil(amount * CENTS);
}

function toUSD(amount) {
  return amount / CENTS;
}

function checkCashRegister(price, cash, cid) {
  const originalDrawer = [...cid];
  var change = toCents(cash - price);
  const billNames = {
    'PENNY': 1,
    'NICKEL': 5,
    'DIME': 10,
    'QUARTER': 25,
    'ONE': 100,
    'FIVE': 500,
    'TEN': 1000,
    'TWENTY': 2000,
    'ONE HUNDRED': 10000,
  }
  var bills = 0;
  var changeGiven = [];
  for(let i = cid.length - 1; i >= 0; i--) {
    let [bill, amount] = cid[i];
    amount = toCents(amount);
    while(change >= billNames[bill] && amount) {
      amount -= billNames[bill];
      change -= billNames[bill];
      bills++; 
    }
    if(bills) {
      changeGiven.push([bill, toUSD(billNames[bill] * bills)]);
      bills = 0;
    }
    if(!amount) {
      cid[i] = null;
    }
  }
  const data = {
    status: 'INSUFFICIENT_FUNDS',
    change: [],
  }

  for(const quid of cid) {
    data.status = 'INSUFFICIENT_FUNDS';
    if(quid) break;
    data.status = 'CLOSED';
  }
  if(data.status == 'CLOSED' && !change) {
    data.change = originalDrawer;
    console.log(data, originalDrawer, change)
    return data;
  }

  if(change) {
    data.status = 'INSUFFICIENT_FUNDS';
    data.change = [];
  }

  if(!change) {
    data.status = 'OPEN';
    data.change = changeGiven;
  };
  return data;

}

checkCashRegister(19.5, 20, [["PENNY", 0.01], ["NICKEL", 0], ["DIME", 0], ["QUARTER", 0], ["ONE", 0], ["FIVE", 0], ["TEN", 0], ["TWENTY", 0], ["ONE HUNDRED", 0]])