ACM&排序问题，操作符重载

对每个测试用例，首先输出1行“Case i:”，其中 i 是测试用例的编号（从1开始）。随后在 N 行中输出按要求排序后的结果，即：当 C=1 时，按学号递增排序；当 C=2时，按姓名的非递减字典序排序；当 C=3 
时，按成绩的非递减排序。当若干学生具有相同姓名或者相同成绩时，则按他们的学号递增排序。

3 1
000007 James 85
000010 Amy 90
000001 Zoe 60
4 2
000007 James 85
000010 Amy 90
000001 Zoe 60
000002 James 98
4 3
000007 James 85
000010 Amy 90
000001 Zoe 60
000002 James 90
0 0

Case 1:
000001 Zoe 60
000007 James 85
000010 Amy 90
Case 2:
000010 Amy 90
000002 James 98
000007 James 85
000001 Zoe 60
Case 3:
000001 Zoe 60
000007 James 85
000002 James 90
000010 Amy 90

http://ac.jobdu.com/problem.php?pid=1023

 1 #include <iostream>
 2 #include <string>
 3 #include <algorithm>
 4 #define NUMSIZE 100010
 5
 6 using namespace std;
 7 int Mode;
 8 class Stu_index {
 9     public:
10         string num;
11         string name;
12         int score;
13         Stu_index(){
14         }
15         Stu_index(string num,string name, int score) {
16             this->num = num;
17             this->name = name;
18             this->score = score;
19         }
20         friend bool operator < (const Stu_index& a, const Stu_index& b) {
21             if(Mode == 1)
22                 return a.num<b.num;
23             if(Mode == 2)
24                 if(a.name!=b.name)  return a.name<b.name;
25                 else return a.num<b.num;
26             if(Mode == 3)
27                 if(a.score!=b.score)    return a.score<b.score;
28                 else return a.num<b.num;
29         }
30         friend bool operator > (const Stu_index& a, const Stu_index& b) {
31             if(Mode == 1)
32                 return a.num>b.num;
33             if(Mode == 2)
34                 if(a.name!=b.name)  return a.name>b.name;
35                 else return a.num>b.num;
36             if(Mode == 3)
37                 if(a.score!=b.score)    return a.score>b.score;
38                 else return a.num>b.num;
39         }
40         friend ostream &operator<< (ostream &os, const Stu_index &item) {
41             os<<item.num<<" "<<item.name<<" "<<item.score;
42             return os;
43         }
44 };
45 /*void quicksort(Stu_index v[], int left, int right) {
46     if(left<right) {
47         Stu_index key = v[left];
48         int low = left;
49         int high = right;
50         while(low<high) {
51             while(low<high && v[high]>key) high--;
52             v[low] = v[high];
53             while(low<high && v[low]<key) low++;
54             v[high] = v[low];
55         }
56         v[low] = key;
57         quicksort(v, left, low-1);
58         quicksort(v, low+1, right);
59     }
60 }*/
61 int main(void) {
62     int N, C;
63     C=0;
64     Stu_index s[NUMSIZE];
65     while(cin>>N && N!=0) {
66         C++;
67         cin>>Mode;
68         for(int i=0; i<N; i++) {
69             cin>>s[i].num>>s[i].name>>s[i].score;
70         }
71         //quicksort(s, 0, N-1);
72         sort(s, s+N);
73         cout<<"Case "<<C<<":"<<endl;
74         for(int i=0; i<N; i++)
75             cout<<s[i]<<endl;
76     }
77     return 0;
78 }

这里使用了重载操作符，但类中的静态变量在没有初始化的时候类中的方法是无法使用改变量的，于是我将Mode改成了全局变量。