Introduction

In this blog post, we will explore how to solve the LeetCode problem "1701" 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

There is a restaurant with a single chef. You are given an array customers, where customers[i] = [arrivali, timei]: arrivali is the arrival time of the ith customer. The arrival times are sorted in non-decreasing order. timei is the time needed to prepare the order of the ith customer. When a customer arrives, he gives the chef his order, and the chef starts preparing it once he is idle. The customer waits till the chef finishes preparing his order. The chef does not prepare food for more than one customer at a time. The chef prepares food for customers in the order they were given in the input. Return the average waiting time of all customers. Solutions within 10-5 from the actual answer are considered accepted. Example 1: Input: customers = [[1,2],[2,5],[4,3]] Output: 5.00000 Explanation: 1) The first customer arrives at time 1, the chef takes his order and starts preparing it immediately at time 1, and finishes at time 3, so the waiting time of the first customer is 3 - 1 = 2. 2) The second customer arrives at time 2, the chef takes his order and starts preparing it at time 3, and finishes at time 8, so the waiting time of the second customer is 8 - 2 = 6. 3) The third customer arrives at time 4, the chef takes his order and starts preparing it at time 8, and finishes at time 11, so the waiting time of the third customer is 11 - 4 = 7. So the average waiting time = (2 + 6 + 7) / 3 = 5. Example 2: Input: customers = [[5,2],[5,4],[10,3],[20,1]] Output: 3.25000 Explanation: 1) The first customer arrives at time 5, the chef takes his order and starts preparing it immediately at time 5, and finishes at time 7, so the waiting time of the first customer is 7 - 5 = 2. 2) The second customer arrives at time 5, the chef takes his order and starts preparing it at time 7, and finishes at time 11, so the waiting time of the second customer is 11 - 5 = 6. 3) The third customer arrives at time 10, the chef takes his order and starts preparing it at time 11, and finishes at time 14, so the waiting time of the third customer is 14 - 10 = 4. 4) The fourth customer arrives at time 20, the chef takes his order and starts preparing it immediately at time 20, and finishes at time 21, so the waiting time of the fourth customer is 21 - 20 = 1. So the average waiting time = (2 + 6 + 4 + 1) / 4 = 3.25. Constraints: 1 <= customers.length <= 105 1 <= arrivali, timei <= 104 arrivali <= arrivali+1

Explanation

• Iterate through the customers array, keeping track of the current time.
  • For each customer, determine the chef's start time (either the customer's arrival time or the time the chef finishes the previous order, whichever is later). Calculate the waiting time and add it to the total waiting time.
  • Calculate and return the average waiting time.

• Runtime Complexity: O(n), where n is the number of customers. Storage Complexity: O(1).

Code

    def averageWaitingTime(customers):
    """
    Calculates the average waiting time of all customers.

    Args:
        customers: A list of lists, where each inner list represents a customer
                   and contains the arrival time and preparation time.

    Returns:
        The average waiting time of all customers.
    """

    total_waiting_time = 0
    current_time = 0

    for arrival_time, preparation_time in customers:
        start_time = max(current_time, arrival_time)
        finish_time = start_time + preparation_time
        waiting_time = finish_time - arrival_time
        total_waiting_time += waiting_time
        current_time = finish_time

    return total_waiting_time / len(customers)