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>
#include <stdlib.h>
#define N 2000000

void sort(int);
void maxheapify(int);
int extract();

int n,arr[N],i=1;
int main(){
  int j,data;
  char com[8];

  while(1){
    scanf("%s",com);
    if(com[0] == 'e' && com[1] == 'n') break;
    else if(com[0] == 'i'){
      scanf("%d",&arr[i]);
      sort(i);
      i++;
    }else{
      i--;
      printf("%d\n",extract());
    }
  }
  return 0;
}

void sort(int node){
  int temp;
  while(node>1 && arr[node/2]<arr[node]){
    temp = arr[node];
    arr[node] = arr[node/2];
    arr[node/2] = temp;
    node=node/2;
  }
}

void maxheapify(int node){
  int left,right,max,temp;
  left=node*2;
  right=node*2+1;
  if(left<=i && arr[left]>arr[node]) max = left;
  else max = node;
  if(right<=i && arr[right]>arr[max]) max = right;
  
  if(max != node){
    temp=arr[node];
    arr[node]=arr[max];
    arr[max]=temp;
    maxheapify(max);
  }
}

int extract(){
  int out=arr[1];
  arr[1]=arr[i];
  maxheapify(1);
  return out;
  
}