2073. Time Needed to Buy Tickets

Problem Link

Description

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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

Solution

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Python3

class Solution:
    def timeRequiredToBuy(self, tickets: List[int], k: int) -> int:
        res = 0
 
        for i, x in enumerate(tickets):
            if i <= k:
                res += min(tickets[k], x)
            else:
                res += min(tickets[k] - 1, x)
        
        return res