这是一个基于M/M/S类型的排队论仿真程序。M/M/S表示到达时间为负指数分布，服务时间为负指数分布，服务设备数量为S个的排队系统。

（1）到达模式：严格意义上讲是一个接着一个到达，而且到达时间间隔服从参数为mean_arr的负指数分布；

（2）服务模式：服务台的数量为server_num,且每个服务台服务一个顾客的服务时间服从参数为mean_serv的负指数分布；

（3）排队规则：满足先进先服务，服务快的先离开的规则。

-This is a based on the M / M / S types of queuing theory simulation program. M / M / S said time of arrival of the negative exponential distribution and service time for the negative exponential distribution, service equipment for the number of S-queuing system. (1) mode of arrival : a strict sense is a one followed arrived, but the inter-arrival time parameters mean_arr obey the negative exponential distribution; (2) mode : The number of help desk server_num. with each help desk services a customer service parameters mean_serv obey the negative exponential distribution; (3) queuing rules : first meet advanced services, the first to leave fast rules.