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>
#include<string.h>
#define MAX 2000000001

int H=0,ary[MAX];

int parent(int i){
  return i/2;
}
int left(int i){
  return 2*i;
}
int right(int i){
  return 2*i+1;
}
void maxheap(int i){
  int l,r,largest,tmp;
  l=left(i);
  r=right(i);
  if(l<=H && ary[l]>ary[i]){largest=l;}
  else{largest=i;}
  if(r<=H && ary[r]>ary[largest]){largest=r;}
  if(largest!=i){
    tmp=ary[i];
    ary[i]=ary[largest];
    ary[largest]=tmp;
    maxheap(largest);
  }
}
int heapextractmax(){
  int max;
  if(H<1){
    fprintf(stderr,"ヒープアンダーフロー\n");
    exit(2);
  }
  max=ary[1];
  ary[1]=ary[H];
  H--;
  maxheap(1);
  return max;
}
void hik(int i,int key){
  int tmp;
  if(key<ary[i]){
    fprintf(stderr,"error\n");
    exit(1);
  }
  ary[i]=key;
  while(i>1 && ary[parent(i)]<ary[i]){
    tmp=ary[i];
    ary[i]=ary[parent(i)];
    ary[parent(i)]=tmp;
    i=parent(i);
  }
}
void insert(int key){
  H++;
  ary[H]=-100000000;
  hik(H,key);
}
int main(){
  int i,value,max;
  char com[10];
  
  while(1){
    scanf("%s",com);
    if(strcmp(com,"insert")==0){
      scanf("%d",&value);
      insert(value);
    }
    if(strcmp(com,"end")==0)break;
    
    else if(strcmp(com,"extract")==0){
      printf("%d\n",heapextractmax());
    }
  }
  return 0;
}