Problem:
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Priority Queue

A priority queue is a data structure which maintains a set $S$ of elements, each of with an associated value (key), and supports the following operations:

$insert(S, k)$: insert an element $k$ into the set $S$

$extractMax(S)$: remove and return the element of $S$ with the largest key

Write a program which performs the $insert(S, k)$ and $extractMax(S)$ operations to a priority queue $S$.
The priority queue manages a set of integers, which are also keys for the priority.

Input

Multiple operations to the priority queue $S$ are given. Each operation is given by "insert $k$", "extract" or "end" in a line. Here, $k$ represents an integer element to be inserted to the priority queue.

The input ends with "end" operation.

Output

For each "extract" operation, print the element extracted from the priority queue $S$ in a line.

Constraints

The number of operations $\leq 2,000,000$

$0 \leq k \leq 2,000,000,000$

Sample Input 1

insert 8
insert 2
extract
insert 10
extract
insert 11
extract
extract
end

Sample Output 1

8
10
11
2

Solution in C (judge verdict: Accepted)

#include <stdio.h>
#define mark -10
int H;
int s[2000000];

void maxheapfy(int i){
     int left = 2*i;
    int right = 2*i +1;
    int largest;
    if(s[i]<s[right] && right<=H) largest = right;
    else largest = i;
    if(s[left]>s[largest] && left<=H ) largest = left;
    
    if(largest != i){
        int tmp = s[largest];
        s[largest] = s[i];
        s[i] = tmp;
        maxheapfy(largest);
    }
    
}

void increasekey(int i,int key){
    if(key<s[i])return;
    s[i] = key;
    while(i>1 && s[i/2]<s[i] ){
        int tmp = s[i];
        s[i] = s[i/2];
        s[i/2] = tmp;
        i = i/2;
    }
    
}
void insert(int a){
    H++;
    s[H] = mark;
    increasekey(H,a);
}

int extract(){
    int maxkey;
    if(H<1)return mark;
    maxkey = s[1];
    s[1] = s[H--];
    maxheapfy(1);
    return maxkey;
    
}
int main(){
    // Your code here!
    int i,k;
    char com[20];
    

   while(1){
        scanf("%s",com);
        if(com[0]=='i'){scanf("%d",&k);
            insert(k);
        }
        if(com[1]=='x'){
        int ex =    extract();
        printf("%d\n",ex);
        }
        if(com[2]=='d'){
            
            break;
        }
        
    }
 
    
}