#include<iostream>
 #include<functional>
 #include<queue>
 using namespace std; struct node
 {
     friend bool operator< (node n1, node n2)
     {
         return n1.priority < n2.priority;//"<"为从大到小排列，">"为从小打到排列
     }
     int priority;
     int value;
 }; int main()
 {
     const int len = 5;
     int i;
     int a[len] = {3,5,9,6,2};
     //示例1
     priority_queue<int> qi;//普通的优先级队列，按从大到小排序
     for(i = 0; i < len; i++)
         qi.push(a[i]);
     for(i = 0; i < len; i++)
     {
         cout<<qi.top()<<" ";
         qi.pop();
     }
     cout<<endl;     //示例2
     priority_queue<int, vector<int>, greater<int> > qi2;//从小到大的优先级队列，可将greater改为less，即为从大到小
     for(i = 0; i < len; i++)
         qi2.push(a[i]);
     for(i = 0; i < len; i++)
     {
         cout<<qi2.top()<<" ";
         qi2.pop();
     }
     cout<<endl;     //示例3
     priority_queue<node> qn;//必须要重载运算符
     node b[len];
     b[0].priority = 6; b[0].value = 1;
     b[1].priority = 9; b[1].value = 5;
     b[2].priority = 2; b[2].value = 3;
     b[3].priority = 8; b[3].value = 2;
     b[4].priority = 1; b[4].value = 4;
  
     for(i = 0; i < len; i++)
         qn.push(b[i]);
     cout<<"优先级"<<'\t'<<"值"<<endl;
     for(i = 0; i < len; i++)
     {
         cout<<qn.top().priority<<'\t'<<qn.top().value<<endl;
         qn.pop();
     }
     return 0;
 } 对于队列里元素为一个结构体类型，按照某一个属性排序，就需要对比较函数进行重载
 小结一下：
 1、若是定义值类型对象，如： 
 int 
  main() 
 {      
     priority_queue<node> qn;     node n1; 
     n1.a = 9; 
     node n2; 
     n2.a = 2; 
     node n3; 
     n3.a = 50;       qn.push(n1);
     qn.push(n2);
     qn.push(n3);
      int  size = qn.size();
      for ( int  i = 0; i < size; i++) 
     { 
         cout << qn.top().a << endl;         qn.pop(); 
     } 
          return  0; } 
 则定义优先级的时候，直接在类中写个friend 的操作符重载函数即可：  class  node 
 { 
 public : 
      int  a;     node(){} 
     node( int  x):a(x){} 
 friend   bool  operator<( const  node ne1, const  node ne2)//参数也可以为引用，值传递 
     { 
          if (ne1.a > ne2.a) 
         { 
              return   true ; 
         } 
          else 
         { 
              return   false ; 
         } 
     } 
 };

class  nodePointerComparer  
 {  
 public :  
     nodePointerComparer(){}  
      bool  operator ()( const  node* ne1,  const  node* ne2)  const   
     {  
          return  ne1->lessthan(ne2);  
     }  
 };   当然在这之前我们的类Node要重新书写 
 class  node  
 {  
 public :  
      int  a;  
     node(){}  
     node( int  x):a(x){}       bool  lessthan( const  node* pnode)  const   
     {  
          return  a < pnode->a;  
     }  
 };  
 这样在main函数中就可以定义指针类型的优先队列了： int  main()  
 {  
     priority_queue <node*, vector <node*>, nodePointerComparer> qn;  
     node *n1 =  new  node(90);  
     node *n2 =  new  node(2);  
     node *n3 =  new  node(50);      qn.push(n1);  
     qn.push(n2); /span> > 
     qn.push(n3);       int  size = qn.size();  
      for ( int  i = 0; i < size; i++)  
     {  
         cout << qn.top()->a << endl;  
         qn.pop();  
     }  
      return  0;  }