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 MAX 2000000
int A[MAX];
int H;

void swap(int *a,int *b){
  int tmp=*a;
  *a=*b;*b=tmp;
}
void maxHeapify(int i){
  int l = 2*i;
  int r = 2*i+1;
  int large;
  
  if(l <= H && A[l] > A[i])
    large = l;
  else
    large = i;
  if(r <= H && A[r] > A[large])
    large = r;

  if(large != i){
    swap(&A[i],&A[large]); 
    maxHeapify(large); 
  }
}
void Insert(int x){
  int i;
  i=H;
  A[i]=x;
  while(i>=2&&A[i/2]<A[i]){
    swap(&A[i],&A[i/2]);
    i=i/2;
  }
}
int extract(void){
  int max;
  max=A[1];
  A[1]=A[H--];
  maxHeapify(1);

  return max;
}

int main(){
  char c[10];
  int i,key;

  while(1){
    scanf("%s",c);
    if(c[0]=='i'){
      H++;
      scanf("%d",&key);
      Insert(key);
    }
    else if(c[1]=='x')
      printf("%d\n",extract());
    else break;
  }
  return 0;
}