电梯调度算法模拟

说明：电梯调度算法的基本原则就是如果在电梯运行方向上有人要使用电梯则继续往那个方向运动，如果电梯中的人还没有到达目的地则继续向原方向运动。具体而言，如果电梯现在朝上运动，如果当前楼层的上方和下方都有请求，则先响应所有上方的请求，然后才向下响应下方的请求；如果电梯向下运动，则刚好相反。-Elevator scheduling algorithm to simulate

Note: the basic principles of the elevator scheduling algorithm is to use the elevator in the elevator running direction to continue in that direction movement, the elevator does not reach the destination continue to apply to the direction of movement. Specifically, if the elevator is now upward movement, if the current floors above and below have a request, the response to all the top of the first request, and then down to respond to the request of the bottom　if the elevator down movement is exactly the opposite.