假设某银行有2个窗口对外接待客户，从早晨银行开门起不断有客户进入银行，由于每个窗口在某个时刻只能接待一个客户。因此在客户人数众多时需要在每个窗口前顺次排队，对于刚进和银行的客户。如果某个窗口的业务员正空闲，则可上前办理业务。反之，若个窗口均有客户所占，他便会排在为数最少的队伍后面。编制一个程序模拟银行的这种业务活动并计算一天中客户在银行的平均逗留时间。

-Suppose there are two windows of a bank' s foreign hospitality customers, banks are open from morning onwards there have been customers into the bank, because each window at a time, only to receive a customer. Therefore, customers need a large number of sequential line up in front of each window, entered, and for the bank' s customers. If a window salesman is free, can be approached to conduct business. Conversely, if the windows are customers of, he would row in behind the ranks of the least number. The preparation of a program to simulate the bank' s business activities and the calculation of this day the customer in the bank' s average length of stay.