这个代码是一个停车场管理系统，关于数据结构的实验，实现停车计费功能，若停车场满了就停在便道里，停车场出去一辆车，便道进去一辆车-This code is a parking management system, experiments on data structures, parking meter, the parking lot full of parked on the sidewalk, parking out of a car, the sidewalk inside a car