ASSIGNMENT
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Design a cash register drawer function checkCashRegister() that accepts purchase price as the first argument (price),
payment as the second argument (cash), and cash-in-drawer (cid) as the third argument.

cid is a 2D array listing available currency.

The checkCashRegister() function should always return an object with a status key and a change key.

Return {status: "INSUFFICIENT_FUNDS", change: []} if cash-in-drawer is less than the change due,
or if you cannot return the exact change.

Return {status: "CLOSED", change: [...]} with cash-in-drawer as the value for the key change if it is equal to the change due.

Otherwise, return {status: "OPEN", change: [...]}, with the change due in coins and bills, sorted in highest to lowest order,
as the value of the change key.
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SOLUTION

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    function checkCashRegister(price, cash, cid) {
      var result = {status: "", change: []};
      // // Here is your change, ma'am.

    var change = cash - price;

    var cashValue = [
      { name: "ONE HUNDRED", value: 100 },
      { name: "TWENTY", value: 20 },
      { name: "TEN", value: 10 },
      { name: "FIVE", value: 5 },
      { name: "ONE", value: 1 },
      { name: "QUARTER", value: 0.25 },
      { name: "DIME", value: 0.1 },
      { name: "NICKEL", value: 0.05 },
      { name: "PENNY", value: 0.01 }
    ];

    var cashInDrowerSum = cid.reduce(function(acc, item) {              // get sum of all money we have in our drawer ('cid')
      return acc + item[1];
    }, 0);

      if (cashInDrowerSum < change) {
        result.status = "INSUFFICIENT_FUNDS";
        return result;
      }

      if (cashInDrowerSum === change) {
        result.status = "CLOSED";
        result.change = cid;
        return result;
      }

    cid = cid.reverse();                     // we are provided with an array ('cid'), where currency units of larger amount come last.
                                             // We need to reverse this array, so that they come in highest to lowest order

    var reduced = cashValue.reduce(function(acc, next, index) {     // we use optional parameter 'index' to get the index (position) of an
                                                                    // element from 'cashValue' array. Then we use this index to get access
                                                                    // to the correspondent element from the previously reversed 'cid' array
                                                                    // (e.g., first element from 'cashValue' array is an
                                                                    // object { name: "Hundred", value: 100 }. Its index is 0.
                                                                    // It corresponds to the first element from the 'cid' array,
                                                                    // ["ONE HUNDRED", 100]).
      var currentValue = 0;
      if (change >= next.value) {
        while (change >= next.value  && cid[index][1] >= next.value) {
          currentValue += next.value; //add next.value-s, until it equals to 'change'
          change -= next.value; // decrement 'change' by the 'next.value' (which we added to the 'currentValue')
          change = Math.round(change * 100) / 100;
          cid[index][1] -= next.value; // take 'next.value' from our drawer
        }
        acc.push([next.name, currentValue]);                  // we provided 'initial value' (see line 83) and set it to an empty array,
                                                              // so 'acc' is equal to an empty array.
                                                              // That is, var reduced = [].push([next.name, currentValue])
        return acc;
      } else {
        return acc;
      }
    }, []);                                                    // we need to provide 2-dimentional array to pass the test,
                                                               // so we need to specify an empty array, as our initial value

    if (reduced.length < 1 || change > 0) {                    // if there are no elements in our 'reduced' array,
                                                               // or if we still owe a change...
                                                               // for example, if we have to give 50 cents,
                                                               // but have only one dollar bill and one penny in our cash in drawer
                                                               // ( checkCashRegister(19.5, 20, [["PENNY", 0.01], ["NICKEL", 0],
                                                               // ["DIME", 0], ["QUARTER", 0], ["ONE", 1], ["FIVE", 0], ["TEN", 0],
                                                               // ["TWENTY", 0], ["ONE HUNDRED", 0]]) )
        result.status = "INSUFFICIENT_FUNDS";
        return result;
       }
       result.status = "OPEN";
       result.change = reduced;
       return result;
    }

    checkCashRegister(19.5, 20, [["PENNY", 1.01], ["NICKEL", 2.05], ["DIME", 3.1], ["QUARTER", 4.25], ["ONE", 90], ["FIVE", 55], ["TEN", 20], ["TWENTY", 60], ["ONE HUNDRED", 100]])