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 2222222
#define INFTY (1<<30)

void maxHeapify(int);
void insert(int);
void increaseKey(int,int);
int heapExtractMax(void);

int H,A[MAX];

int main(){
  int key;
  char c[10];
  A[H] = -INFTY;

  while(1){
    scanf("%s",c);
    if(c[0] == 'e' && c [1] =='n'){
      break;
    }
    if(c[0] == 'i'){
      scanf("%d",&key);
      insert(key);
    }
    else{
      printf("%d\n",heapExtractMax());
    }
  }
  return 0;
}
void maxHeapify(int i){
  int l,r;
  int max,keep;
  l = 2*i;
  r = 2*i+1;
  if(l <= H && A[l] >A[i]) {
    max = l;
  }
  else{
    max = i;
  }
  if(r <= H&& A[r] >A[max]) {
    max = r;
  }

  if(max != i){
    keep = A[i];
    A[i] = A[max];
    A[max] = keep;
    maxHeapify(max);
  }
}

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

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

int heapExtractMax(){
  int max;
  if (H < 1){
    return -INFTY;
  }
  max = A[1];
  A[1] = A[H];
  H--;
  maxHeapify(1);
  return max;
}