成绩排序

思路：用algorithm的sort函数对键值对进行排序（需自定义比较函数，这里是我需要学习的），最后输出。
自定义的比较函数逻辑，比如比较整数s1和s2，如果要使s1小于s2时是真，则return s1<s2；使s1大于s2时是真，则return s1>s2。

#include<iostream>
#include<string>
#include<algorithm>
using namespace std;

struct student
{
    string name;
    int score;
    int num;
};

int cmp1(student &s1, student &s2)
{
    if (s1.score == s2.score)
        return s1.num < s2.num;
    else
        return s1.score < s2.score;
}

int cmp0(student &s1, student &s2)
{
    if (s1.score == s2.score)
        return s1.num < s2.num;
    else
        return s1.score > s2.score;
}


int main()
{
    int count, method;
    while (cin >> count && cin >> method) {
        student *list = new student[count];
        for (int i = 0; i < count; ++i) {
            cin >> list[i].name >> list[i].score;
            list[i].num = i;
        }
        //排序
        if (method == 1)//升序
            sort(list, list + count, cmp1);
        else//降序
            sort(list, list + count, cmp0);
        for (int i = 0; i < count; ++i)
            cout << list[i].name << " " << list[i].score << endl;
    }
    system("pause");
    return 0;
}