所给的代码最顶端是最小的元素

要改为最顶端是最大的则只需把

friend  bool operator<(Node a, Node b) { return  a.val > b.val; } 

改成

friend  bool operator<(Node a, Node b) { return  a.val < b.val; } 

即可。

#include <iostream>

#include <queue>

using namespace std;

struct Node

{

    int adj;

    int val;

    friend  bool operator<(Node a, Node b) { return  a.val > b.val; }

};

priority_queue<Node>Q;

Node temp;

int main()

{

    temp.val = 2;

    Q.push(temp);

    temp.val = 29;

    Q.push(temp);

    temp.val = 67;

    Q.push(temp);

    temp.val = 17;

    Q.push(temp);

    while (!Q.empty())

    {

        temp = Q.top();

        printf("%d\n", temp.val);

        Q.pop();

    }

    return 0;

}