设计一个停车场系统，有一个停车场和一个便道。当当有车到达时，如果停车场内有空位，那么车进停车场；如没有空位就看便道是否有空位，如有就把车停入便道。如果便道也满了就停入别的停车场。-Design a parking system, there is a parking lot and a sidewalk. Dangdang a car arrives, if there is space parking lot, then drive into the parking lot if there