PAT1017 Queueing at Bank

    　　本题解题思路是先对输入进行按照时间到达的先后顺序进行排序，然后依次模拟到达窗口，对每个窗口有一个空闲时间，表示该窗口能够处理下一个客户的最近时间。将每个客户到达的时间按照格式转化成秒，用户的时间total和窗口的空闲时间比较，若大于则说明用户到达时窗口是空闲的，就不需要等待；若小于则需要遍历所有窗口，查找空闲窗口，若不存在空闲窗口，则计算所有窗口中最近空闲时间的那个窗口，对其进行更新时间。

　　　　代码如下：

#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
typedef struct Record
{
    int hour;
    int minute;
    int second;
    int wait_time;
    int total;
}Record_record;

typedef struct Waitline
{
    int end_time;
}Waitline_record;

vector <Record_record> record_list;
vector <Waitline_record> wait_list;


bool compare(const Record_record &a, const Record_record &b)
{
    if (a.total < b.total)
    {
        return true ;
    }
    else
    {
        return false ;
    }
}

int cal_min_wait()
{
    int i;
    int min = wait_list[0].end_time;
    int index = 0;
    for (i = 0; i < wait_list.size(); i++ )
    {
        if (min > wait_list[i].end_time)
        {
            min = wait_list[i].end_time;
            index = i;
        }
    }

    return index;
}

int main()
{
    int i,j;
    int num,window_num;
    int hour,minute,second;
    int wait_time;
    int count = 0;
    int total_wait_time = 0;
    int rest_time;
    int min;
    //enter the num
    cin>>num>>window_num;

    for (i = 0; i < num; i++)
    {
        Record_record record;
        scanf( "%d:%d:%d" ,&hour,&minute,&second);
        scanf( "%d" ,&wait_time);

        if (hour>=17 && (minute != 0 || second != 0))
        {
            continue ;
        }

        record.hour = hour;
        record.minute = minute;
        record.second = second;
        record.total = hour*3600 + minute*60+second;
        record.wait_time = wait_time*60;
        record_list.push_back(record);
        count++;
    }

    for (i = 0; i < window_num; i++)
    {
        Waitline_record wait_window;
        wait_window.end_time = 28800;
        wait_list.push_back(wait_window);
    }

    sort(record_list.begin(),record_list.end(),compare);

    for (i = 0; i < count; i++)
    {
        //在8点前都算等待时间
        if (record_list[i].hour < 8)
        {
            total_wait_time += 28800-record_list[i].total;
            record_list[i].total = 28800;
        }
        for (j = 0; j < window_num; j++)
        {
            //判断到达时间在某窗口空闲时间之前，还是之后，之前的话查找其他窗口是否空闲；    
            if (record_list[i].total >= wait_list[j].end_time)
            {
                //若该窗口空闲，无需等待，则该用户在此窗口处理，更新此窗口的空闲时间节点
                wait_list[j].end_time = record_list[i].total+record_list[i].wait_time;
                break ;
            }

        }
        //若该用户到达时没有空闲窗口
        if (j == window_num)
        {
            //等待空闲时间节点最短的那个窗口
            min = cal_min_wait();
            //等待直到时间最近窗口空闲
            total_wait_time += wait_list[min].end_time - record_list[i].total;
            //更新窗口的最近空闲时间
            wait_list[min].end_time += record_list[i].wait_time;
        }

    }

    double wait_min =(double ) total_wait_time /60;
　　　　 double average;
　　　　  if(count != 0)
      average = wait_min / count;
　　 else
　　　　　　average = 0.0;

    printf( "%.1lf
" ,average);

    return 0;
}