Análisis : clasificación pura de estructuras, no hay nada que decir, solo ordena
#include <iostream>
#include<cstring>
#include<vector>
#include<stdio.h>
#include<queue>
#include<math.h>
#include<stack>
#include<algorithm>
#include<map>
#include<set>
#define MAX 99999999
using namespace std;
typedef long long ll;
struct stu{
string id,name;
int grade;
};
int cmp1(stu s1,stu s2)
{
if(s1.id != s2.id) return s1.id < s2.id;
}
int cmp2(stu s1,stu s2)
{
if(s1.name != s2.name) return s1.name <= s2.name;
return s1.id < s2.id;
}
int cmp3(stu s1,stu s2)
{
if(s1.grade != s2.grade) return s1.grade <= s2.grade;
return s1.id < s2.id;
}
int main()
{
int n,m;
cin>>n>>m;
stu s[n];
for(int i = 0;i<n;i++)
cin>>s[i].id>>s[i].name>>s[i].grade;
if(m == 1)
sort(s,s+n,cmp1);
if(m == 2)
sort(s,s+n,cmp2);
if(m == 3)
sort(s,s+n,cmp3);
for(int i = 0;i<n;i++)
cout<<s[i].id<<" "<<s[i].name<<" "<<s[i].grade<<endl;
return 0;
}