pb_ds priority_queue

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/priority_queue.hpp>

using namespace std;
using namespace __gnu_pbds;

typedef __gnu_pbds::priority_queue<int, less<int>, pairing_heap_tag> heap;

int main()
{
    int arr1[] = {9, 0, 1, 2, 5, 3, 4, 7, 6, 8};
    int arr2[] = {19, 10, 11, 12, 15, 13, 14, 17, 16, 18};

    heap pq1, pq2;

    //push()
    for(auto it : arr1)
        pq1.push(it);
    for(auto it : arr2)
        pq2.push(it);


    //top(), pop(), size(), empty()
    printf("pq1: ");
    while(pq1.size())
    {
        printf("%d ", pq1.top());
        pq1.pop();
    }
    puts("");

    printf("pq2: ");
    while(!pq2.empty())
    {
        printf("%d ", pq2.top());
        pq2.pop();
    }
    puts("");


    //push()
    for(auto it : arr1)
        pq1.push(it);
    for(auto it : arr2)
        pq2.push(it);


    //join()
    pq1.join(pq2);

    printf("pq1.join(pq2): ");
    while(pq1.size())
    {
        printf("%d ", pq1.top());
        pq1.pop();
    }
    puts("");

    return 0;
}
/**
OUTPUT:
pq1: 9 8 7 6 5 4 3 2 1 0
pq2: 19 18 17 16 15 14 13 12 11 10
pq1.join(pq2): 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
**/