The Fair-Share Multi-Channel Scheduler

You are building a task scheduler for multiple users. Each user has their own FIFO queue of tasks. To ensure fairness, the scheduler uses a 'User-Level Round Robin' strategy: 1. Maintain a queue of *active users* (users who have at least one task pending). 2. In each step, pick the user at the front of the active user queue. 3. Process exactly one task from that user's FIFO queue. 4. If that user still has tasks left, move the user to the back of the active user queue. Otherwise, remove them from the active user queue. 5. New tasks can arrive at any time. If a task arrives for a user not currently in the active user queue, that user is added to the *back* of the active user queue. Input: N (number of tasks). Each task is `Timestamp UserID TaskID`. Tasks are sorted by Timestamp. Output: The sequence of `TaskID` in the order they are processed. Example: Input: 4 0 Alice T1 0 Bob T2 0 Alice T3 5 Charlie T4 Output: T1 T2 T3 T4