快速掌握优先队列-代码

// priority_queue using function
#include<cstdio>
#include<algorithm>
#include<queue>
#include<functional>
using namespace std;
struct node {
    friend bool operator < (const node& a, const node& b) {
        return a.x< b.x;
    }
    int x;
};
node a[10];
int main() {
    //默认是从大到小
    priority_queue<int> que;
    for (int i = 0; i < 5; i++) {
        que.push(i);
    }

    for (int i = 0; i < 5; i++) {
        printf("%d ", que.top());
        que.pop();
    }
    printf("\n");
    //less是从大到小输出；greater是从小到大输出，greater/less 的头文件是functional
    priority_queue<int, vector<int>, less*<int>> que1;
    for (int i = 10; i < 15; i++) {
        que1.push(i);
    }
    for (int i = 10; i < 15; i++) {
        printf("%d ", que1.top());
        que1.pop();
    }
    printf("\n");
    /*结构体必须要对 < 重载，return...>...是从小到大；return.....<.....是从大到小；
    如果对 > 重载的话，无论你return..... < 或 >都是从大到小，其实很简单，因为在对优先队列源码其实使用的是 < 。*/
    priority_queue<node> que2;
    node a;
    for (int i = 20; i < 25; i++) {
        a.x = i;
        que2.push(a);
    }
    for (int i = 20; i < 25; i++) {
        printf("%d ", que2.top());
        que2.pop();
    }
    return 0;
}