能实现总体清零功能：计数器由初始状态开始计数，对应状态的指示灯亮 能实现特殊状态的功能显示：进入特殊状态时，东西、南北路口均显示红灯状态 -Functions to achieve overall clear: counter starts counting from the initial state, the corresponding status indicator light to achieve the special status of function display: