知识点

• 这题的数据比较大，得用scanf，而且要换全都换，不然还是会超时

• 结构体重载符号，只能重载一次。所以只能选择写三个比较函数。

• string不能用scanf来读入，所以可以用中间值转换一下，字符数组。

  然后再转回字符串时，需要用到 c_str() （用来将字符数组转为字符串！）

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

using namespace std;

const int N = 100010;

struct Records
{
    string id, name;
    int grade;

}records[N];

bool cmp1(Records a, Records b)
{
    return a.id < b.id;
}

bool cmp2(Records a, Records b)
{
    if (a.name != b.name) return a.name < b.name;
    return a.id < b.id;
}

bool cmp3(Records a, Records b)
{
    if (a.grade != b.grade) return a.grade < b.grade;
    return a.id < b.id;
}

int main()
{
    int n, c;
    scanf("%d%d", &n, &c);

    for (int i = 0; i < n; i ++ )
    {
        char id[10], name[10];
        int grade;
        scanf("%s %s %d", id, name, &grade);

        records[i] = {id, name, grade};
    }


    if (c == 1) sort(records, records + n, cmp1);
    else if (c == 2) sort(records, records + n, cmp2);
    else sort(records, records + n, cmp3);

    for (int i = 0; i < n; i ++ )
        printf("%s %s %d\n", records[i].id.c_str(), records[i].name.c_str(), records[i].grade);

    return 0;
}