Problem of The Day: Display Table of Food Orders in a Restaurant

6 min read 1297 words

Problem Statement

leetcode problem link

Solution [Accepted]

class Solution:
    def displayTable(self, orders: List[List[str]]) -> List[List[str]]:
        mapping = {}
        tables = set()
        foods = set()
        for customerName, tableNumber, foodItem in orders:
            if tableNumber not in mapping:
                mapping[tableNumber] = {}
            if foodItem not in mapping[tableNumber]:
                mapping[tableNumber][foodItem] = 0

            mapping[tableNumber][foodItem] += 1
            tables.add(tableNumber)
            foods.add(foodItem)

        sorted_foods = [food for food in sorted(foods)]
        foodIndices = {food: i + 1 for i, food in enumerate(sorted_foods)}
        sorted_tables = sorted(tables, key=lambda x:int(x))
        headers = ["Table"] + sorted_foods
        res = [headers]

        for table in sorted_tables:
            curr = [table]
            for _ in range(len(sorted_foods)):
                curr.append("0")
            arr = []
            for food, numOfOrder in mapping[table].items():
                index = foodIndices[food]
                curr[index] = str(numOfOrder)
            res.append(curr[:])
        return res

using System;
using System.Collections.Generic;
using System.Linq;

public class Solution
{
    public IList<IList<string>> DisplayTable(IList<IList<string>> orders)
    {
        // Map: tableNumber -> (food -> count)
        var tableFood = new Dictionary<int, Dictionary<string, int>>();
        var foods = new HashSet<string>();
        var tables = new HashSet<int>();

        foreach (var order in orders)
        {
            int table = int.Parse(order[1]);  // "12" -> 12
            string food = order[2];

            if (!tableFood.TryGetValue(table, out var foodMap))
            {
                foodMap = new Dictionary<string, int>();
                tableFood[table] = foodMap;
            }
            foodMap[food] = foodMap.TryGetValue(food, out var c) ? c + 1 : 1;

            tables.Add(table);
            foods.Add(food);
        }

        var sortedFoods = foods.OrderBy(f => f, StringComparer.Ordinal).ToList();
        var sortedTables = tables.OrderBy(t => t).ToList();

        var result = new List<IList<string>>(sortedTables.Count + 1);

        // Header
        var header = new List<string>(sortedFoods.Count + 1) { "Table" };
        header.AddRange(sortedFoods);
        result.Add(header);

        // Rows
        foreach (var table in sortedTables)
        {
            var row = new string[sortedFoods.Count + 1];
            row[0] = table.ToString();

            var foodMap = tableFood[table];
            for (int i = 0; i < sortedFoods.Count; i++)
            {
                string food = sortedFoods[i];
                row[i + 1] = foodMap.TryGetValue(food, out int cnt) ? cnt.ToString() : "0";
            }
            result.Add(row);
        }

        return result;
    }
}

using System;
using System.Collections.Generic;

public class Solution
{
    public IList<IList<string>> DisplayTable(IList<IList<string>> orders)
    {
        var tableFood = new Dictionary<int, Dictionary<string, int>>();
        var foods = new SortedSet<string>(StringComparer.Ordinal);
        var tables = new SortedSet<int>();

        foreach (var order in orders)
        {
            int table = int.Parse(order[1]);
            string food = order[2];

            if (!tableFood.TryGetValue(table, out var foodMap))
            {
                foodMap = new Dictionary<string, int>();
                tableFood[table] = foodMap;
            }
            foodMap[food] = foodMap.TryGetValue(food, out var c) ? c + 1 : 1;

            tables.Add(table);
            foods.Add(food);
        }

        var sortedFoods = new List<string>(foods);
        var result = new List<IList<string>>(tables.Count + 1);

        var header = new List<string>(sortedFoods.Count + 1) { "Table" };
        header.AddRange(sortedFoods);
        result.Add(header);

        foreach (var table in tables)
        {
            var row = new string[sortedFoods.Count + 1];
            row[0] = table.ToString();

            var foodMap = tableFood[table];
            for (int i = 0; i < sortedFoods.Count; i++)
            {
                string food = sortedFoods[i];
                row[i + 1] = foodMap.TryGetValue(food, out int cnt) ? cnt.ToString() : "0";
            }
            result.Add(row);
        }

        return result;
    }
}