1418. 点菜展示表

# 题目

## 1418. 点菜展示表

[https://leetcode-cn.com/problems/display-table-of-food-orders-in-a-restaurant/](https://leetcode-cn.com/problems/display-table-of-food-orders-in-a-restaurant/)

给你一个数组 `orders`，表示客户在餐厅中完成的订单，确切地说， `orders[i]=[customerNamei,tableNumberi,foodItemi]` ，其中 `customerNamei` 是客户的姓名，`tableNumberi` 是客户所在餐桌的桌号，而 `foodItemi` 是客户点的餐品名称。

请你返回该餐厅的 **点菜展示表** *。*在这张表中，表中第一行为标题，其第一列为餐桌桌号 “Table” ，后面每一列都是按字母顺序排列的餐品名称。接下来每一行中的项则表示每张餐桌订购的相应餐品数量，第一列应当填对应的桌号，后面依次填写下单的餐品数量。

注意：客户姓名不是点菜展示表的一部分。此外，表中的数据行应该按餐桌桌号升序排列。

**示例 1：**

```
输入：orders = [["David","3","Ceviche"],["Corina","10","Beef Burrito"],["David","3","Fried Chicken"],["Carla","5","Water"],["Carla","5","Ceviche"],["Rous","3","Ceviche"]]
输出：[["Table","Beef Burrito","Ceviche","Fried Chicken","Water"],["3","0","2","1","0"],["5","0","1","0","1"],["10","1","0","0","0"]] 
解释：
点菜展示表如下所示：
Table,Beef Burrito,Ceviche,Fried Chicken,Water
3    ,0           ,2      ,1            ,0
5    ,0           ,1      ,0            ,1
10   ,1           ,0      ,0            ,0
对于餐桌 3：David 点了 "Ceviche" 和 "Fried Chicken"，而 Rous 点了 "Ceviche"
而餐桌 5：Carla 点了 "Water" 和 "Ceviche"
餐桌 10：Corina 点了 "Beef Burrito"
```

**示例 2：**

```
输入：orders = [["James","12","Fried Chicken"],["Ratesh","12","Fried Chicken"],["Amadeus","12","Fried Chicken"],["Adam","1","Canadian Waffles"],["Brianna","1","Canadian Waffles"]]
输出：[["Table","Canadian Waffles","Fried Chicken"],["1","2","0"],["12","0","3"]] 
解释：
对于餐桌 1：Adam 和 Brianna 都点了 "Canadian Waffles"
而餐桌 12：James, Ratesh 和 Amadeus 都点了 "Fried Chicken"
```

**示例 3：**

```
输入：orders = [["Laura","2","Bean Burrito"],["Jhon","2","Beef Burrito"],["Melissa","2","Soda"]]
输出：[["Table","Bean Burrito","Beef Burrito","Soda"],["2","1","1","1"]]
```

**提示：**

- `1 <= orders.length <= 5 * 10^4`
- `orders[i].length == 3`
- `1 <= customerNamei.length, foodItemi.length <= 20`
- `customerNamei` 和 `foodItemi` 由大小写英文字母及空格字符 `' '` 组成。
- `tableNumberi` 是 `1` 到 `500` 范围内的整数。

# 题解

## 思路

理清思路，把餐桌号和食物做对应关系，用Map和Set两个数据结果填充数据。

## 代码

```javascript
/**
 * @param {string[][]} orders
 * @return {string[][]}
 */
var displayTable = function (orders) {
    // 餐桌和食物映射
    let tableMap = new Map();
    // 食物集合
    let foodSet = new Set();
    orders.forEach(order => {
        let food;
        // 餐桌号转成数字
        let table = Number(order[1]);
        if (tableMap.has(table)) {
            // 获取食物的映射
            food = tableMap.get(table);
            // 设置份数
            food.set(order[2], (food.get(order[2]) || 0) + 1);
            tableMap.set(table, food);
        } else {
            food = new Map().set(order[2], 1);
            tableMap.set(table, food);
        }
        // 添加到集合中
        foodSet.add(order[2]);
    });
    // 返回的结果，第一行是食物，按字母排序
    let ans = [Array.from(foodSet).sort()];
    // 获取餐桌号，从小到大排序
    let tableOrder = Array.from(tableMap.keys()).sort((a, b) => a - b);
    // 封装数据
    tableOrder.forEach(item => {
        let res = [item];
        // 食物映射关系
        let foodMap = tableMap.get(item);
        ans[0].forEach(food => {
            // 不存在则设置成0
            res.push(foodMap.get(food) || 0);
        });
        ans.push(res);
    });
    // 在第一行增加Table
    ans[0].unshift('Table');
    // 处理成字符串
    return ans.map(item => item.map(String));
};
```