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Solving Leetcode Interviews in Seconds with AI: Time Needed to Buy Tickets

Updated
3 min read

Introduction

In this blog post, we will explore how to solve the LeetCode problem "2073" 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 are n people in a line queuing to buy tickets, where the 0th person is at the front of the line and the (n - 1)th person is at the back of the line. You are given a 0-indexed integer array tickets of length n where the number of tickets that the ith person would like to buy is tickets[i]. Each person takes exactly 1 second to buy a ticket. A person can only buy 1 ticket at a time and has to go back to the end of the line (which happens instantaneously) in order to buy more tickets. If a person does not have any tickets left to buy, the person will leave the line. Return the time taken for the person initially at position k (0-indexed) to finish buying tickets. Example 1: Input: tickets = [2,3,2], k = 2 Output: 6 Explanation: The queue starts as [2,3,2], where the kth person is underlined. After the person at the front has bought a ticket, the queue becomes [3,2,1] at 1 second. Continuing this process, the queue becomes [2,1,2] at 2 seconds. Continuing this process, the queue becomes [1,2,1] at 3 seconds. Continuing this process, the queue becomes [2,1] at 4 seconds. Note: the person at the front left the queue. Continuing this process, the queue becomes [1,1] at 5 seconds. Continuing this process, the queue becomes [1] at 6 seconds. The kth person has bought all their tickets, so return 6. Example 2: Input: tickets = [5,1,1,1], k = 0 Output: 8 Explanation: The queue starts as [5,1,1,1], where the kth person is underlined. After the person at the front has bought a ticket, the queue becomes [1,1,1,4] at 1 second. Continuing this process for 3 seconds, the queue becomes [4] at 4 seconds. Continuing this process for 4 seconds, the queue becomes [] at 8 seconds. The kth person has bought all their tickets, so return 8. Constraints: n == tickets.length 1 <= n <= 100 1 <= tickets[i] <= 100 0 <= k < n

Explanation

  • Simulate the ticket buying process, incrementing the time for each ticket bought.
    • Keep track of the number of tickets each person has remaining.
    • Stop the simulation when the target person at index k has no more tickets to buy.
  • Runtime Complexity: O(N*M), where N is the number of people and M is the maximum number of tickets any person has initially. Space Complexity: O(1).

Code

    def time_to_buy_tickets(tickets, k):
    """
    Calculates the time taken for the person at index k to finish buying tickets.

    Args:
        tickets: A list of integers representing the number of tickets each person wants to buy.
        k: The index of the person we are interested in.

    Returns:
        The time taken for the person at index k to finish buying tickets.
    """

    n = len(tickets)
    time = 0
    while tickets[k] > 0:
        for i in range(n):
            if tickets[i] > 0:
                tickets[i] -= 1
                time += 1
                if i == k and tickets[k] == 0:
                    return time

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