PAT甲级练习题A1017. Queueing at Bank (25)

题目描述

Suppose a bank has K windows open for service. There is a yellow line in front of the windows which devides the waiting area into two parts. All the customers have to wait in line behind the yellow line, until it is his/her turn to be served and there is a window available. It is assumed that no window can be occupied by a single customer for more than 1 hour.

Now given the arriving time T and the processing time P of each customer, you are supposed to tell the average waiting time of all the customers.

Input Specification:

Each input file contains one test case. For each case, the first line contains 2 numbers: N (<=10000) - the total number of customers, and K (<=100) - the number of windows. Then N lines follow, each contains 2 times: HH:MM:SS - the arriving time, and P - the processing time in minutes of a customer. Here HH is in the range [00, 23], MM and SS are both in [00, 59]. It is assumed that no two customers arrives at the same time.

Notice that the bank opens from 08:00 to 17:00. Anyone arrives early will have to wait in line till 08:00, and anyone comes too late (at or after 17:00:01) will not be served nor counted into the average.

Output Specification:

For each test case, print in one line the average waiting time of all the customers, in minutes and accurate up to 1 decimal place.

Sample Input:
7 3
07:55:00 16
17:00:01 2
07:59:59 15
08:01:00 60
08:00:00 30
08:00:02 2
08:03:00 10
Sample Output:
8.2

题目解析

模拟排队，根据来的时间顺序排队，依次在最先空出来的窗口接收服务；
注意区别来了就有空位的情况；
注意在17点之后来的不接收服务，不计数；

代码

#include<iostream>#include<vector>#include<algorithm>using namespace std;struct person{    int hh, mm, ss, arr, take, leav, proc;};int main(){    int N, K;    cin >> N >> K;    vector<person> group;    vector<int>window_leave(K, 8 * 60 * 60);    for (int i = 0; i < N; ++i)    {        person per;        scanf("%d:%d:%d %d", &per.hh, &per.mm, &per.ss, &per.proc);        per.arr = per.hh * 60 * 60 + per.mm * 60 + per.ss;        group.push_back(per);    }    sort(group.begin(), group.end(), [](person &a, person &b) {return a.arr<b.arr; });    int cnt = 0;    for (; cnt < N&&group[cnt].arr < 17 * 60 * 60 + 1; ++cnt)    {        int min_w = 0;//找最先空出来的窗口        for (int i = 1; i < K; ++i)        {            if (window_leave[i] < window_leave[min_w])                min_w = i;        }        if (window_leave[min_w] > group[cnt].arr)//注意区别来了就有空位的情况        {            group[cnt].take = window_leave[min_w];            group[cnt].leav = window_leave[min_w] + group[cnt].proc * 60;        }        else        {            group[cnt].take = group[cnt].arr;            group[cnt].leav = group[cnt].arr + group[cnt].proc * 60;        }        window_leave[min_w] = group[cnt].leav;    }    double sum = 0;    for (int i = 0; i < cnt; ++i)    {        sum += (group[i].take - group[i].arr);    }    printf("%.1f\n", sum / 60 / cnt);    system("pause");    return 0;}