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)

int H,A[MAX+1];

void maxHeapify(int);
int extract(void);
void increaseKey(int,int);
void insert(int);
void swap(int *,int *);

int main(){
  int key;
  char s[10];

  while(1){
    scanf("%s",s);
    if(s[0] == 'e' && s[1] == 'n')break;

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

  return 0;
}

void maxHeapify(int i){ 
int l,r,larg,tmp;

  l = 2 * i;
  r = 2 * i + 1;

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

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

  if(larg != i){
    tmp = A[i];
    A[i] = A[larg];
    A[larg] = tmp;
    maxHeapify(larg);
  }

}

int extract(void){
  int maxv;

  if(H < 1)return -INFTY;

  maxv = A[1];
  A[1] = A[H--];
  maxHeapify(1);

  return maxv;
}

void increaseKey(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;
  increaseKey(H,key);
}

void swap(int *a,int *b){
  int tmp;

  tmp = *a;
  *a = *b;
  *b = tmp;
}