2017 中心笔试题目 最短作业优先（SJF）

#include <iostream>
#include <vector>
#include <stdlib.h>
#include <algorithm>

using namespace std;
/********************题目要求***********************************
最短左右优先，输出总等待时间
测试用例：
任务：    A，B，C，D
请求时间：0，2，4，5
持续时间：7，4，1，4
求平均等待时间
****************************************************************/
/********************解题思路***********************************
  
  
  
      请求时间   持续时间  开始时间  结束时间   等待时间 = 开始时间 - 请求时间
A        0          7         0         7           0
----------------------------------------------------------
C        4          1         7         8           3
----------------------------------------------------------
B        2          4         8         12          6
----------------------------------------------------------
D        5          4         12        16          7

****************************************************************/

void show(vector<int> &time)
{
    for (int i = 0; i < time.size(); i++)
        cout << time[i] << "   ";
}
float average_time(vector<int> &require_time, vector<int> &duration_time, int n)
{
    for (int i = 0; i < n - 1; i++)
    {
        for (int j = i + 1; j < n; j++)
        {
            if ((duration_time[i] > duration_time[j]) || ((duration_time[i] == duration_time[j]) && (require_time[i] > require_time[j])))
            {
                duration_time[i] = duration_time[i] ^ duration_time[j];
                duration_time[j] = duration_time[i] ^ duration_time[j];
                duration_time[i] = duration_time[i] ^ duration_time[j]; 
                require_time[i] = require_time[i] ^ require_time[j];
                require_time[j] = require_time[i] ^ require_time[j];
                require_time[i] = require_time[i] ^ require_time[j];
            }
        }
    }
    int min = 0xFFFFFFFF, count = 0;
    vector<int> start_time(n), end_time(n),wait_time(n);
    int sum = 0;
    for (int i = 0; i < require_time.size(); i++)
    {
        if (require_time[i] < min)
        {
            min = require_time[i];
            count = i;
        }
        else if (min == require_time[i])
        {
            count = duration_time[count] < duration_time[i] ? duration_time[count] : duration_time[i];
        }
    }
    duration_time.insert(duration_time.begin(), duration_time[count]);
    duration_time.erase(duration_time.begin()+ count + 1);
    require_time.insert(require_time.begin(), require_time[count]);
    require_time.erase(require_time.begin() + count + 1);
    start_time[0] = require_time[0];
    end_time[0] = duration_time[0];
    wait_time[0] = 0;
    for (int i = 1; i < n; i++)
    {
        start_time[i] = end_time[i - 1];
        end_time[i] = start_time[i] + duration_time[i];
        wait_time[i] = start_time[i] - require_time[i];
        sum += wait_time[i];
    }
    return (float)(sum / n);
}


int main()
{
    int task_list = 0;
    cin >> task_list;
    vector<int> require_time, duration_time;
    int time0 = 0, time1 = 0;
    int temp = task_list;
    while (temp--)
    {
        cin >> time0 >> time1;
        require_time.push_back(time0);
        duration_time.push_back(time1);
    }
    cout << average_time(require_time, duration_time, task_list) << endl;
    
    system("pause");
}