Time Needed to Buy Tickets - Solution & Explanation

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.

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.