PAT A1028 List Sorting

PAT A1028 List Sorting

题目描述：

　　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 (≤10​5​​) 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 90

　　Sample Output 3:
　　000001 Zoe 60
　　000007 James 85
　　000002 James 90
　　000010 Amy 90

参考代码：

/**************************************************
PAT A1028 List Sorting
**************************************************/
#include <iostream>
#include <algorithm>
#include <vector>

using namespace std;

struct StuRecord {
    string id;
    string name;
    int grade = 0;
};

//自定义比较函数
bool cmpById(StuRecord a, StuRecord b) { return  a.id < b.id; }
bool cmpByName(StuRecord a, StuRecord b) { return a.name == b.name ? a.id < b.id : a.name < b.name; }
bool cmpByGrade(StuRecord a, StuRecord b) { return a.grade == b.grade ? a.id < b.id : a.grade < b.grade; }
bool(*cmp[3])(StuRecord, StuRecord) = { cmpById, cmpByName, cmpByGrade };

int main() {
    vector<StuRecord> recordList;
    int recordCnt = 0, compareFunc = 0;

    cin >> recordCnt >> compareFunc;

    //读入记录
    StuRecord temp;
    for (int i = 0; i < recordCnt; ++i) {
        cin >> temp.id >> temp.name >> temp.grade;
        recordList.push_back(temp);
    }

    //按照指定方式进行排列
    sort(recordList.begin(), recordList.end(), cmp[compareFunc - 1]);

    //输出排列结果
    for (int i = 0; i < recordList.size(); ++i) {
        cout << recordList[i].id << ' ' << recordList[i].name << ' ' << recordList[i].grade;
        if (i != recordList.size() - 1) cout << endl;
    }

    return 0;
}

注意事项：

　　1：递增顺寻排列和非递减顺序排列实质上是一样的。

　　2：注意函数指针的使用；指针相关的操作见下文（待补充）：