You are given activity logs for a ride-sharing app. Each log entry indicates that two riders shared a ride at a certain time, which creates an undirected connection between them (they can “reach” each other either directly or through other riders). ## Problem Given: - An integer `n` = number of riders, labeled `0..n-1`. - A list `logs`, where each entry is `[timestamp, a, b]` meaning rider `a` and rider `b` shared a ride at `timestamp`. Return the **earliest timestamp** at which **all riders become mutually connected** (i.e., the graph of riders becomes a single connected component). If this never happens, return `-1`. ### Notes / Constraints - `logs` may be unsorted. - Multiple logs can share the same timestamp. - You may assume `0 <= a, b < n`, `a != b`. - Choose reasonable time and space complexity for large inputs (e.g., up to `1e5` logs). ## Follow-up (harder variant) Now suppose riders can also **block** each other. A block means two riders should be treated as **not connected**, even if there is a path between them that would otherwise connect them. You may model this as additional events like `[timestamp, "BLOCK", x, y]` (and optionally `[timestamp, "UNBLOCK", x, y]`). Discuss how you would modify your approach to support block events, and how you would determine the earliest time when all riders are mutually connected under these constraints.