这题比较简单，结构体存放三个数据，根据C的不同选择比较函数，sort

原题链接

#include <iostream>
#include <cstdio>
#include <algorithm>

using namespace std;

struct Stu
{
    int id;
    string name;
    int grade;
}stu[100000];

bool cmp1(Stu &s1, Stu &s2)
{
    return s1.id < s2.id;
}

bool cmp2(Stu &s1, Stu &s2)
{
    if (s1.name != s2.name)
        return s1.name < s2.name;
    else
        return s1.id < s2.id;
}

bool cmp3(Stu &s1, Stu &s2)
{
    if (s1.grade != s2.grade)
        return s1.grade < s2.grade;
    else
        return s1.id < s2.id;
}

int main()
{
    int N, C;
    scanf("%d %d", &N, &C);
    for (int i=0; i<N; i++)
        cin >> stu[i].id >> stu[i].name >> stu[i].grade;
    if (C == 1)
        sort(stu, stu+N, cmp1);
    else if (C == 2)
        sort(stu, stu+N, cmp2);
    else
        sort(stu, stu+N, cmp3);
    for (int i=0; i<N; i++)
    {
        printf("%06d ",stu[i].id);
        cout<<stu[i].name<<' '<<stu[i].grade<<'\n';
    }
    return 0;
}