Streaming Latest-Per-Message Log Processor

Implement a streaming log processor. Logs arrive one at a time through add_log(timestamp, message). For each message, only the entry with the greatest timestamp is valid. The processor must support: add_log(timestamp, message): add a log entry. It may invalidate a previously valid entry for that message. get_next(): return the valid, not-yet-returned entry with the smallest timestamp as (timestamp, message). Return None if no such entry exists. Once get_next() returns an entry, that entry must not be returned again. Lazy deletion is allowed: old entries may remain in a heap, but they must be recognized and skipped when popped. For equal timestamps, get_next() must return the lexicographically smaller message first. Operation example add_log(5, "a") add_log(2, "b") add_log(8, "a") get_next() -> (2, "b") get_next() -> (8, "a") get_next() -> None Constraints At most 2 * 10^5 operations. Timestamps are signed 64-bit integers. Example Input 6 add 5 a add 2 b add 8 a get get get Output 2 b 8 a None