c++ priority_queue

1、默认为大顶堆

 #include <iostream>
 #include <queue>
 using namespace std;

 int main()
 {
     priority_queue<int> p;
     int i;
     for (i = ; i < ; i++)
         p.push(i);
     for (i = ; i < ; i++)
     {
         cout << p.top() << " ";
         p.pop();
     }
     return ;
 }

运行结果：

2、小顶堆

 int main()
 {
     priority_queue<int, vector<int>, greater<int>> p;
     //vs2013需要#include <functional>
     int i;
     for (i = ; i < ; i++)
         p.push(i);
     for (i = ; i < ; i++)
     {
         cout << p.top() << " ";
         p.pop();
     }
     return ;
 }

运行结果：

3、自定义

 #include <iostream>
 #include <queue>
 using namespace std;

 struct Node
 {
     int a, b;
     Node(int x, int y) : a(x), b(y) {}
 };

 struct cmp
 {
     bool operator() (Node *x, Node *y)
     {
         if (x->a != y->a) return x->a < y->a; //大顶堆
         return x->b < y->b;
     }
 };
 int main()
 {

     priority_queue<Node *, vector<Node *>, cmp> p;
     Node *n = new Node(, ); p.push(n);
     n = new Node(, ); p.push(n);
     n = new Node(, ); p.push(n);
     while (!p.empty())
     {
         n = p.top();
         p.pop();
         cout << n->a << " " << n->b << endl;
     }
     return ;
 }

运行结果：