我校科技楼北楼有两台电梯。等电梯的人给出要上下的信号，电梯只有在空闲或同方向行进时才接受这个指令。然而，电梯经常出现十分拥挤的状况，特别在上下课的时候，要等很长的时间，所以埋怨声很多。你能否为电梯设计一个调度方案，减少大家的等待时间，减少师生的不满。-Our School Building North Building has two elevators. Such as elevators were given to the signal from top to bottom, the lift only when the idle or the same direction when the road to accept this command. However, the elevators are often very crowded, particularly in the last class when we have to wait a very long time, so many complain about the sound. Are you able to lift the design of a scheduling scheme to reduce the waiting time for everyone to reduce the dissatisfaction of the teachers and students.