Leetcode 2073. Time Needed to Buy Tickets

Given a list tickets[] and index k, compute how many seconds until person k finishes in a round-robin queue where each second the front buys one ticket and (if they still need more) goes to the back. The core challenge is counting how many times each person will be served before k completes (i.e., summing each person's contributions limited by k's remaining tickets and their position).