Design Check-In System

Instructions

Design a system that tracks employees and the time they spend in the office, built up over two levels:

1. Check-ins — add employees and record when they enter or leave the office.
2. Reporting — query how long an employee has worked in total.

Interfaces

class CheckInSystem:
    def add_employee(self, employee_id: str, position: str, compensation: int) -> bool: ...
    def register(self, employee_id: str, timestamp: int) -> str: ...
    def get_total_time(self, employee_id: str) -> int: ...

Level 1: Check-Ins

Implement add_employee and register.

• add_employee(employee_id, position, compensation) adds the employee along with their position and compensation. Returns True on success, or False if employee_id already exists (nothing changes). employee_id and position contain only English letters and spaces.
• register(employee_id, timestamp) records an office event; calls arrive in strictly increasing timestamp order. If the employee is currently out of the office, this records a check-in; if currently in, it records a check-out. Returns "registered" on success, or "invalid_request" if employee_id does not exist.

cs.add_employee("Ashley", "Engineer", 150)   # True
cs.add_employee("Ashley", "Manager", 200)    # False — ID already exists

cs.register("Ashley", 10)                    # "registered" — Ashley checks in
cs.register("Ashley", 25)                    # "registered" — Ashley checks out
cs.register("Walter", 30)                    # "invalid_request" — unknown employee

Function signature:

class CheckInSystem:
    def __init__(self):
        pass

    def add_employee(self, employee_id: str, position: str, compensation: int) -> bool:
        pass

    def register(self, employee_id: str, timestamp: int) -> str:
        pass

Level 2: Reporting

Add get_total_time(employee_id), which returns the total time the employee has spent in the office, or -1 if employee_id does not exist.

Only completed sessions count: if an employee has checked in but not yet checked out, that open visit is excluded from the total.

cs.add_employee("Ashley", "Engineer", 150)   # True

cs.register("Ashley", 10)                    # check in
cs.register("Ashley", 25)                    # check out — session of 15
cs.register("Ashley", 40)                    # check in  — still in the office

cs.get_total_time("Ashley")                  # 15 — the open visit at t=40 is not counted
cs.get_total_time("Walter")                  # -1

Function signature:

class CheckInSystem:
    def __init__(self):
        pass

    def add_employee(self, employee_id: str, position: str, compensation: int) -> bool:
        pass

    def register(self, employee_id: str, timestamp: int) -> str:
        pass

    def get_total_time(self, employee_id: str) -> int:
        pass