Introduction

In this blog post, we will explore how to solve the LeetCode problem "1418" using AI. LeetCode is a popular platform for preparing for coding interviews, and with the help of AI tools like Chatmagic, we can generate solutions quickly and efficiently - helping you pass the interviews and get the job offer without having to study for months.

Problem Statement

Given the array orders, which represents the orders that customers have done in a restaurant. More specifically orders[i]=[customerNamei,tableNumberi,foodItemi] where customerNamei is the name of the customer, tableNumberi is the table customer sit at, and foodItemi is the item customer orders. Return the restaurant's “display table”. The “display table” is a table whose row entries denote how many of each food item each table ordered. The first column is the table number and the remaining columns correspond to each food item in alphabetical order. The first row should be a header whose first column is “Table”, followed by the names of the food items. Note that the customer names are not part of the table. Additionally, the rows should be sorted in numerically increasing order. Example 1: Input: orders = [["David","3","Ceviche"],["Corina","10","Beef Burrito"],["David","3","Fried Chicken"],["Carla","5","Water"],["Carla","5","Ceviche"],["Rous","3","Ceviche"]] Output: [["Table","Beef Burrito","Ceviche","Fried Chicken","Water"],["3","0","2","1","0"],["5","0","1","0","1"],["10","1","0","0","0"]] Explanation: The displaying table looks like: Table,Beef Burrito,Ceviche,Fried Chicken,Water 3 ,0 ,2 ,1 ,0 5 ,0 ,1 ,0 ,1 10 ,1 ,0 ,0 ,0 For the table 3: David orders "Ceviche" and "Fried Chicken", and Rous orders "Ceviche". For the table 5: Carla orders "Water" and "Ceviche". For the table 10: Corina orders "Beef Burrito". Example 2: Input: orders = [["James","12","Fried Chicken"],["Ratesh","12","Fried Chicken"],["Amadeus","12","Fried Chicken"],["Adam","1","Canadian Waffles"],["Brianna","1","Canadian Waffles"]] Output: [["Table","Canadian Waffles","Fried Chicken"],["1","2","0"],["12","0","3"]] Explanation: For the table 1: Adam and Brianna order "Canadian Waffles". For the table 12: James, Ratesh and Amadeus order "Fried Chicken". Example 3: Input: orders = [["Laura","2","Bean Burrito"],["Jhon","2","Beef Burrito"],["Melissa","2","Soda"]] Output: [["Table","Bean Burrito","Beef Burrito","Soda"],["2","1","1","1"]] Constraints: 1 <= orders.length <= 5 * 10^4 orders[i].length == 3 1 <= customerNamei.length, foodItemi.length <= 20 customerNamei and foodItemi consist of lowercase and uppercase English letters and the space character. tableNumberi is a valid integer between 1 and 500.

Explanation

Here's a solution to the "Display Table of Food Orders in a Restaurant" problem, focusing on efficiency and clarity.

• Collect Data: Iterate through the orders array to store the number of each food item ordered at each table in a suitable data structure like a dictionary of dictionaries.
• Create Header and Table Rows: Extract the unique food items and table numbers. Sort the food items alphabetically and table numbers numerically. Then, generate the header row and table rows based on the collected order counts.

• Format Output: Combine the header and table rows into the final output list of lists.

• Runtime Complexity: O(N log N + M log M), where N is the number of orders and M is the number of unique food items/tables. Sorting contributes to the log N and log M factors. Storage Complexity: O(N + M), to store the orders and the unique food items/tables.

Code

    from collections import defaultdict

def displayTable(orders):
    """
    Returns the restaurant's display table based on the input orders.

    Args:
        orders: A list of lists, where each inner list represents an order
                in the format [customerName, tableNumber, foodItem].

    Returns:
        A list of lists representing the display table.
    """

    table_orders = defaultdict(lambda: defaultdict(int))
    food_items = set()
    tables = set()

    for order in orders:
        customer, table, food = order
        table = int(table)
        table_orders[table][food] += 1
        food_items.add(food)
        tables.add(table)

    food_items = sorted(list(food_items))
    tables = sorted(list(tables))

    header = ["Table"] + food_items
    result = [header]

    for table in tables:
        row = [str(table)]
        for food in food_items:
            row.append(str(table_orders[table][food]))
        result.append(row)

    return result