每到达一个顾客，即为该类顾客取一个随机数作为该类顾客下一个到达时刻的间隔，其他两类顾客的下一个到达间隔保持上一个值不变，然后取三个间隔中的最小值作为下一个顾客将要到达的时刻。这似乎破坏了随机性，但是若不这样，每到达一个顾客即更新三类顾客的到达间隔值，结果是20000顾客下来，到达的全都是最低优先级的顾客。-Every arrival of a customer and such customers shall take a random number of such customers as the next arrival time interval, the other two types of customers arrive at the next interval to maintain a constant value, and then check the three intervals of the minimum as the next customer to arrive at the moment. This seems to undermine the randomness, but if so, for every arrival of a customer and is updated as the three types of customers arrive at interval value, resulting in 20,000 customers down, all reach the lowest-priority customers.