Problem:
MathJax.Hub.Config({ tex2jax: { inlineMath: [["$","$"], ["\\(","\\)"]], processEscapes: true }});

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>
#include<math.h>

void insert(int *,int);
void maxHeapify(int *,int);
int extractMax(int *);
void buildMaxHeap(int *,int);
void increasekey(int *,int,int);

int H=0;

int main()
{
  char c[10];
  int k,S[2000000];
 
  while(1)
    {
      scanf(" %s",c);
  
	  if(c[0] == 'i')
	    {
	      scanf("%d",&k);
	      insert(S,k);
	    }
	  else if(c[1] == 'x')
	    {
	      printf("%d\n",extractMax(S));
	    }
	  else break;
    }
  return 0;
}

void insert(int *A,int k)
{
  H++;
  A[H] = -300;
  
  increasekey(A,H,k);
  
  return;
}

void increasekey(int *A,int i,int k)
{
  int change;
  if(k < A[i]) exit(2);

  A[i] = k;

  while(i > 1 && A[i/2] < A[i])
    {
      change = A[i];
      A[i] = A[i/2];
      A[i/2] = change;

      i = i/2;
    }
  
  return;
}

void maxHeapify(int *A,int i)
{
  int l,r,largest,change;

  l = 2*i; //left
  r = 2*i+1; //right

  if(l <= H && A[l] > A[i]) largest = l;
  else largest = i;

  if(r <= H && A[r] > A[largest]) largest = r;

  if(largest != i)
    {
      change = A[i];
      A[i] = A[largest];
      A[largest] = change;
      
      maxHeapify(A,largest);
    }
  
  return;
}

int extractMax(int *S)
{
  int max;
  
  if(H < 1) exit(1);

  max = S[1];
  S[1] = S[H];
  H--;
  maxHeapify(S,1);

  return max;
}