依照一个存着新进货物的二维数组，更新存着现有库存(在 arr1 中)的二维数组. 如果货物已存在则更新数量 . 如果没有对应货物则把其加入到数组中，更新最新的数量. 返回当前的库存数组，且按货物名称的字母顺序排列.
function updateInventory(arr1, arr2) {
// All inventory must be accounted for or you're fired!
for (var i = 0; i < arr1.length; i++) {
for (var j = 0; j < arr2.length; j++) {
if (arr1[i][1] == arr2[j][1]) {
arr1[i][0] += arr2[j][0];
arr2.splice(j, 1);
j--;
}
}
}
arr1 = arr1.concat(arr2);
return arr1.sort(function(x, y) {
return x[1] > y[1]; // 字符串可以比较大小 但不能进行-操作 （str1 - str2 一般会返回 NaN）
});
}
// Example inventory lists
var curInv = [
[21, "Bowling Ball"],
[2, "Dirty Sock"],
[1, "Hair Pin"],
[5, "Microphone"]
];
var newInv = [
[2, "Hair Pin"],
[3, "Half-Eaten Apple"],
[67, "Bowling Ball"],
[7, "Toothpaste"]
];
updateInventory(curInv, newInv);
// [[88,"Bowling Ball"],[2,"Dirty Sock"],[3,"Hair Pin"],[3,"Half-Eaten Apple"],[5,"Microphone"],[7,"Toothpaste"]]