1028. List Sorting

List Sorting

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

Input

Each input file contains one test case. For each case, the first line contains two integers N (<=100000) 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

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 90

Sample Output 3

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

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题意

给定一组学生数据，包括学号、姓名、成绩，要求按照指定的列升序排列，如果姓名或成绩相同则按学号升序排列。

思路

直接使用sort写好比较函数即可，需要注意的是不要用iostream来输入输出，不然最后一个测试点会TLE。

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代码实现

#include <cstdio>
#include <cstring>
#include <vector>
#include <algorithm>
using namespace std;

struct Student
{
    int id;
    char name[9];
    int grade;
};

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

bool cmp2(Student a, Student b)
{
    if (!strcmp(a.name, b.name))
        return a.id < b.id;
    else
        return strcmp(a.name, b.name) < 0;
}

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

int main()
{
    int n, c;
    Student x;
    vector<Student> stu;

    scanf("%d %d", &n, &c);
    for (int i = 0; i < n; i++)
    {
        scanf("%d %s %d", &x.id, x.name, &x.grade);
        stu.push_back(x);
    }

    if (c == 1)
        sort(stu.begin(), stu.end(), cmp1);
    else if (c == 2)
        sort(stu.begin(), stu.end(), cmp2);
    else if (c == 3)
        sort(stu.begin(), stu.end(), cmp3);

    for (int i = 0; i < n; i++)
        printf("%06d %s %d\n", stu[i].id, stu[i].name, stu[i].grade);

    return 0;
}