Parcel Tracking System — Event Recording and Querying

Problem: Parcel Tracking System (Level 1) Implement a simplified parcel tracking system. Each parcel is identified by a unique string parcelId. A parcel may have multiple event types, each identified by a string eventType. The system maintains a running count for every (parcelId, eventType) pair. Implement ParcelTrackingSystem with the following methods: record_event(parcel_id: str, event_type: str, count: int) -> int Record an event of type event_type for parcel parcel_id and increase its running count by count. If the parcel or event type does not exist yet, create it with running count count. Return the updated running count. get_event_count(parcel_id: str, event_type: str) -> int | None Return the current running count for event_type on parcel parcel_id. Return None if either the parcel or event type does not exist. remove_event(parcel_id: str, event_type: str) -> bool Remove the complete record for event_type from parcel parcel_id. Return True if a record was removed; otherwise return False. If removing the event leaves the parcel with no event types, remove the parcel as well. Example record_event("A", "B", 5) -> 5 record_event("A", "B", 6) -> 11 get_event_count("A", "B") -> 11 get_event_count("A", "C") -> None remove_event("A", "B") -> True remove_event("A", "B") -> False CLI Input Format The first line contains an integer q, followed by q operations: RECORD <parcelId> <eventType> <count> GET <parcelId> <eventType> REMOVE <parcelId> <eventType> Print the return value of every operation. Print null for None, and lowercase true / false for Boolean values. Constraints parcelId and eventType are whitespace-free strings. count is an integer. The original prompt does not state a bound for q; target expected O(1) time per operation. The screenshot lists a 40-second execution limit and a 4-GB memory limit. Example Input 6 RECORD A B 5 RECORD A B 6 GET A B GET A C REMOVE A B REMOVE A B Output 5 11 11 null true false