1028 List Sorting （PAT甲级）

#include <cstdio>
#include <vector>
#include <algorithm>
#include <string>

struct stu{
    int id;
    std::string name;
    int grade;
};

int N, C;
char name[9];
std::vector<stu> vec;

bool cmp(const stu &a, const stu &b){
    if(C == 1){
        return a.id < b.id;
    } else if(C == 2){
        return a.name != b.name ? a.name < b.name : a.id < b.id;
    } else{
        return a.grade != b.grade ? a.grade < b.grade : a.id < b.id;
    }
}

int main(){
    scanf("%d %d", &N, &C);
    vec.resize(N);
    for(int i = 0; i < N; ++i){
        scanf("%d %s %d", &vec[i].id, name, &vec[i].grade);
        vec[i].name = name;
    }
    sort(vec.begin(), vec.end(), cmp);
    for(int i = 0; i < N; ++i){
        printf("%06d %s %d\n", vec[i].id, vec[i].name.c_str(), vec[i].grade);
    }
    return 0;
}

题目如下：

Excel can sort records according to any column. Now you are supposed to imitate this function.

Input Specification:

Each input file contains one test case. For each case, the first line contains two integers N (≤105) and C, where N is the number of records and C is the column that you are supposed to sort the records with. Then N lines follow, each contains a record of a student. A student's record consists of his or her distinct ID (a 6-digit number), name (a string with no more than 8 characters without space), and grade (an integer between 0 and 100, inclusive).

Output Specification:

For each test case, output the sorting result in N lines. That is, if C = 1 then the records must be sorted in increasing order according to ID's; if C = 2 then the records must be sorted in non-decreasing order according to names; and if C = 3 then the records must be sorted in non-decreasing order according to grades. If there are several students who have the same name or grade, they must be sorted according to their ID's in increasing order.

Sample Input 1:

3 1
000007 James 85
000010 Amy 90
000001 Zoe 60

Sample Output 1:

000001 Zoe 60
000007 James 85
000010 Amy 90

Sample Input 2:

4 2
000007 James 85
000010 Amy 90
000001 Zoe 60
000002 James 98

Sample Output 2:

000010 Amy 90
000002 James 98
000007 James 85
000001 Zoe 60

Sample Input 3:

4 3
000007 James 85
000010 Amy 90
000001 Zoe 60
000002 James 9

Sample Output 3:

000002 James 9
000001 Zoe 60
000007 James 85
000010 Amy 90