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 (≤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 90
Sample Output 3:
000001 Zoe 60
000007 James 85
000002 James 90
000010 Amy 90
参考代码：
1 /**************************************************
2 PAT A1028 List Sorting
3 **************************************************/
4 #include <iostream>
5 #include <algorithm>
6 #include <vector>
7
8 using namespace std;
9
10 struct StuRecord {
11 string id;
12 string name;
13 int grade = 0;
14 };
15
16 //自定义比较函数
17 bool cmpById(StuRecord a, StuRecord b) { return a.id < b.id; }
18 bool cmpByName(StuRecord a, StuRecord b) { return a.name == b.name ? a.id < b.id : a.name < b.name; }
19 bool cmpByGrade(StuRecord a, StuRecord b) { return a.grade == b.grade ? a.id < b.id : a.grade < b.grade; }
20 bool(*cmp[3])(StuRecord, StuRecord) = { cmpById, cmpByName, cmpByGrade };
21
22 int main() {
23 vector<StuRecord> recordList;
24 int recordCnt = 0, compareFunc = 0;
25
26 cin >> recordCnt >> compareFunc;
27
28 //读入记录
29 StuRecord temp;
30 for (int i = 0; i < recordCnt; ++i) {
31 cin >> temp.id >> temp.name >> temp.grade;
32 recordList.push_back(temp);
33 }
34
35 //按照指定方式进行排列
36 sort(recordList.begin(), recordList.end(), cmp[compareFunc - 1]);
37
38 //输出排列结果
39 for (int i = 0; i < recordList.size(); ++i) {
40 cout << recordList[i].id << ' ' << recordList[i].name << ' ' << recordList[i].grade;
41 if (i != recordList.size() - 1) cout << endl;
42 }
43
44 return 0;
45 }
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）：