C++ set 多级排序 多维度排序

#include <iostream>  
#include <set>  
#include<algorithm>
using namespace std;  

    /*Student结构体*/   
    struct Student {  
    string name;  
    int id;  
    int score;  
    };  

        /*“仿函数"。为Student set指定排序准则*/  
        class studentSortCriterion {  
        public:  　　　　　　　/*类型要与set容器类型一致*/
            bool operator() (const Student *a, const Student *b) const {  
                return (a->id == b->id) ? (a->score > b->score) :(a->id > b->id);
            }  
        };  


int main()  
{  
    set<Student*, studentSortCriterion> stuSet;  
    set<Student*> stus;

    Student stu1, stu2,stu3;  
    stu1.name = "张三";  
    stu1.id =2;
    stu1.score = 100;  

    stu2.name = "李四";  
    stu2.id = 1;
    stu2.score = 90;  

    stu3.name = "小明";
    stu3.id = 3;
    stu3.score = 80;

    stuSet.insert(&stu1);  
    stuSet.insert(&stu2);
    stuSet.insert(&stu3);   

    Student stuTem;
    stuTem.score = 80;
    stuTem.id = 3;
    Student* stuTempPtr;  
    set<Student*, studentSortCriterion>::iterator iter;  
    iter = stuSet.find(&stuTem);  
    if(iter != stuSet.end()) {  
    　　cout << (*iter)->name << endl;  
    }　　 else {  
    　　cout << "Cannot find the student!" << endl;  
    }  

    for(std::set<Student*,studentSortCriterion>::iterator it = stuSet.begin();it!=stuSet.end();it++ ){
        std::cout<<(*it)->name<<endl;
    }
}      

上面程序会根据学生ID先进行排名然后再根据分数进行排名，排序准则需要满足以下要求，摘自C++标准库第二版：

输出结果：

小明

小明

张三