LeetCode 1600/1610 (uncertain) with follow-up

You are given a coding interview problem from the company’s question bank (the candidate recalled it as “1600/1610”, exact ID uncertain) and a follow-up variation. Tasks: Implement a solution for the main problem. Implement or explain the follow-up requirement (e.g., adding an operation, changing constraints, or adding extra queries on top of the original problem). Input/output format and constraints: follow the interviewer’s specification.