Process Moderator Audit Logs: Order Moderators by Last Add Time

Problem: Process Moderator Logs (Return Moderators Ordered by Last Add Time) You are given a very large string log containing multiple lines of moderator audit records. Each line describes an operation with comma-separated fields: <target_mod>,<action>,<actor_mod>,<timestamp> target_mod: the moderator being acted on (string) action: either add or remove actor_mod: the moderator who performed the action (string) timestamp: an integer timestamp (comparable) Implement a method that takes the log string and returns a List[str]: Return the usernames who are currently moderators Sort them by the timestamp of their most recent add operation in ascending order If two moderators have the same last-add timestamp, break ties by username lexicographically I/O Input: string log with N lines (N >= 0) Output: List[str] Constraints 0 <= N <= 2e5 Each line length <= 200 timestamp fits in 64-bit integer Example Input: mod2,add,mod1,100 mod3,add,mod2,101 mod2,remove,mod3,102 mod2,add,mod1,103 Output: ["mod3", "mod2"] Example Input mod2,add,mod1,100 mod3,add,mod2,101 mod2,remove,mod3,102 mod2,add,mod1,103 Output ["mod3", "mod2"]