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
#define INFTY (1<<30)
#define SWAP(a,b) (a^=b,b=a^b,a^=b)
int H, A[MAX+1];
void maxHeapify(int i){
  int l,r,largest;
  l=2*i;
  r=2*i+1;
  if(l<=H&&A[l]>A[i]) largest=l;
  else largest=i;
  if(r<=H&&A[r]>A[largest]) largest=r;
  if(largest!=i){
    SWAP(A[i],A[largest]);
    maxHeapify(largest);
  }
}
int extract(){
  int maxv;
  if(H<1) return -INFTY;
  maxv=A[1];
  A[1]=A[H--];
  maxHeapify(1);
  return maxv;
}
void kansuu(int i,int key){
  if(key<A[i]) return;
  A[i]=key;
  while(i>1&&A[i/2]<A[i]){
    SWAP(A[i],A[i/2]);
    i=i/2;
  }
}
void insert(int key){
  H++;
  A[H]=-INFTY;
  kansuu(H,key);
}
int main(void){
  int key;
  char com[10];

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