← 返回 bloomberg 的题目列表Event Registration System
类型：online_judge
Design a system to manage event registration. The system should have the following functions: 1. Register() to register a user 2. unRegister() to deregister a user 3. topK() to get the IDs of the top K registered users. Ensure users are maintained in registration order and returned accordingly.
Example
Input
Register()
Register()
topK(1)