First Unique Visitor ID Retrieval with O(1) Query

amazon Assume there is a website where people come to visit. Please design and implement two functions: record_visit(person_id: int) -> None: Record the ID of each person visiting the site. find_first_visitor() -> int: Find the ID of the first person who visited the website only once. If there is no such user, return -1. Requirements: The record_visit function may be called a very large number of times n, up to 10^5. The find_first_visitor function should complete in almost O(1) time. Example Suppose record_visit is called in sequence as follows: record_visit(2) record_visit(3) record_visit(3) record_visit(4) record_visit(5) Calling find_first_visitor() should return 2, as 2 is the only person who visited the site and did so only once. Constraints User IDs are integers and positive. All inputs are stored in memory; persistence is not required. Example Input print(find_first_visitor())