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>
int p = 0, q[2000000];

int max_num(int x, int y){
    if(q[x]>q[y])
        return x;
    else   
        return y;
}

void insert(int k){
    int i, j, temp;
    p++;
    q[p] = k;
    i = p;
    while(q[i] > q[i/2] && i > 1){
        temp = q[i];
        q[i] = q[i/2];
        q[i/2] = temp;
        i = i/2;
    }
}

int extract(){
    int i, temp, max, a;
    a = q[1];
    q[1] = q[p];
    p--;
    i = 1;
    while(i*2 <= p){
        if(i*2+1<=p)    max = max_num(i*2, i*2+1);
        else    max =i*2;
        if(max_num(max, i)==max){
            temp = q[max];
            q[max] = q[i];
            q[i] = temp;
            i = max;
        }
        else break;
    }
    return a;
}

int main(){
    int i, j, k;
    char A[10];
    while(1){
        scanf("%s",A);
        if(A[0]=='i'){
            scanf("%d",&k);
            insert(k);
        }
        if(A[0]=='e' && A[1]=='x')
            printf("%d\n",extract());
        if(A[0]=='e' && A[1]=='n')  break;
    }
    return 0;
}