main166.cpp

queue的说明请看：http://www.360doc.com/content/13/0912/17/3373961_314003806.shtml

#include <iostream>
#include <queue>
#include <cstdlib>
#include <ctime>
using namespace std;
//我懒得分开多个了，直接从前面的复制过来了
class Customer  
{  
private:  
    long arrive;  
    int processtime;  
public:  
    Customer(){arrive=processtime=0;};  
    void set(long when){  
        processtime=rand()%3+1;  
        arrive=when;  
    }  
    long when()const{  
        return arrive;  
    }  
    int ptime()  
    {  
        return processtime;  
    }  
    friend ostream&operator<<(ostream &os,const Customer &c)//用于检测  
    {  
        static int j=0;  
        os<<j++<<"  arrive:"<<c.arrive<<"    need time:"<<c.processtime<<endl;  
        return os;  
    }  
};  
  
typedef Customer Item;  

const int MIN_PER_HR=60;
bool newCustomer(double x)//每隔x次，rand()/RAND_max会有一次值<1
{
	return rand()*x/RAND_MAX<1;
}
void main166()
{
	srand(time(0));//初始化rand();
	cout<<"Case Study:Bank of Heather Automatic Teller"<<endl;
	cout<<"Enter maximum size of queue:";
	int qs;
	cin>>qs;
	queue<Item> line;//queue模板没有大小一说

	cout<<"Enter the number of simulation hours:";
	int hours;
	cin>>hours;
	long cyclelimit=MIN_PER_HR*hours;//循环的分钟数

	cout<<"Enter the average number of customers per hour:";//一个小时来的人数
	double perhour;
	cin>>perhour;
	double min_per_cust;
	min_per_cust=MIN_PER_HR/perhour;//平均多少分钟来一个人


	Item temp;
	long turnaways=0;
	long customers=0;
	//long served=0;
	long served=0;
	long sum_line=0;
	int wait_time=0;
	long line_wait=0;

	for(int cycle=0;cycle<cyclelimit;cycle++)//cycle每循环一次，代表过了一分钟
	{
		//line.s();
		if(newCustomer(min_per_cust))
		{
			if(line.size()==qs)//这样就代表满了
				turnaways++;//拒绝服务？？？//恩,应该就是拒绝服务的人数
			else
			{
				customers++;//队列人数//应该是顾客人数+1而不是队列人数+1
				temp.set(cycle);//cycle是到达时间
				line.push(temp);//入队列

			}

		}
		if(wait_time<=0&&line.size()!=0)//用户处理完了业务
		{
			line.pop();//出队列，不会返回值
			//cout<<"after the delete"<<line;//test
			wait_time=temp.ptime();//wait_time是该客户处理业务所用时间
			line_wait+=cycle-temp.when();//cycle-temp.when();是该客户一共在队列中等了多久
			//一开始wait_time初始化是0，然后进入这里之后，又重新设置了使其=processtime
			//line_wait是该队列一共等了多久？？哦，应该是所有客户的等待时间
			//line_wait是客户等待总时间
			served++;//服务人数+1
		}

		if(wait_time>0)//正在处理业务的处理时间-1，因为过了一分钟
			wait_time--;//话说这wait_time是谁设置了？一直=0？
		//wait_time=temp.ptime()这里随机设置了wait-time
		sum_line+=line.size();//sum_line又是神马东东？？
		//sum_line是队伍总长度，每分钟计算一次队伍长度
	}

	if(customers>0)
	{
		cout<<"customers accepted:"<<customers<<endl;
		cout<<"		customers served:"<<served<<endl;
		cout<<"			turnaways:"<<turnaways<<endl;
		cout<<"average queue size:";
		cout.precision(2);
		cout.setf(ios_base::fixed,ios_base::floatfield);
		cout<<(double)sum_line/cyclelimit<<endl;
		cout<<"average wait time:"<<(double)line_wait/served<<"  minutes"<<endl;
	}//我机器上面是18人最接近1分钟，队列长度10,时间100
	else
		cout<<"No coustomer!"<<endl;
	cout<<"Done!"<<endl;
	system("pause");
}