Time Needed to Buy Tickets

Problem Description

Ah, the classic dilemma of waiting in line for tickets! You know the drill: you’re standing in a queue, and the person in front of you is taking their sweet time, as if they’re deciding whether to buy a ticket or just stare at the counter for a while. The problem is simple yet relatable: given a list of ticket counts for each person in line and your position in that line, how long will it take for you to buy your ticket?

Imagine you’re at a concert, and the person ahead of you is contemplating whether to buy a VIP pass or just a regular ticket. Meanwhile, you’re just trying to get in before the opening act starts. The struggle is real!

Code Solution

class Solution:
    def timeRequiredToBuy(self, tickets: list[int], k: int) -> int:
        ans = 0

        for i, ticket in enumerate(tickets):
            if i <= k:
                ans += min(ticket, tickets[k])
            else:
                ans += min(ticket, tickets[k] - 1)

        return ans

Approach

The approach here is straightforward: we iterate through the list of tickets. For each person in line, we check if they are ahead of you (index k). If they are, we add the minimum of their tickets or your ticket count to the total time. If they are behind you, we add the minimum of their tickets or one less than your ticket count. This way, we account for the fact that you’ve already bought your ticket.

Time and Space Complexity

Time Complexity: O(n), where n is the number of people in line. We traverse the list of tickets once.

Space Complexity: O(1), as we are using a constant amount of space for our variables.

Real-World Example

Picture this: you’re at a movie theater, and the line is moving slower than a snail on a leisurely stroll. The person in front of you is debating whether to buy popcorn or just go for the ticket. Meanwhile, you’re calculating how many minutes you’ll miss of the movie. This problem mirrors that scenario perfectly! The solution helps you figure out how long you’ll be stuck in that line, contemplating life choices.