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 1000000
#define INFTY (1<<21)

int n,A[MAX+1];

void maxHeapify(int i)
{
  int left,right,largest,a;
  left=2*i;
  right=2*i+1;
  if(left<=n && A[left]>A[i])
    largest=left;
  else
    largest=i;
  if(right<=n && A[right]>A[largest])
    largest=right;
  if(largest!=i)
    {
      a=A[i];
      A[i]=A[largest];
      A[largest]=a;
      maxHeapify(largest);
    }
}

int extract()
{
  int x;
  if(n<1)
    return -INFTY;
  x=A[1];
  A[1]=A[n--];
  maxHeapify(1);
  return x;
}

void increaseKey(int i,int key)
{
  int a;
  if(key<A[i])
    return;
  A[i]=key;
  while(i>1 && A[i/2] < A[i])
    {
      a=A[i];
      A[i]=A[i/2];
      A[i/2]=a;
      i/=2;
    }
}

void insert(int key)
{
  n++;
  A[n]=-INFTY;
  increaseKey(n,key);
}

int main()
{
  int k;
  char com[10];

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