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>
#include<limits.h>
 
 
int A[2000000];
int n;
 
int parent(int i){
    return i/2;
}
int left(int i){
  return 2*i;
}
  
int right(int i){
  return 2*i+1;
}
 
 
void maxHeapify(int i){
int l = left(i);
int r = right(i);
 int largest,temp;
  if( l <= n && A[l] > A[i]){
    largest = l;
  }
  else{
    largest = i;
  }
  if(r <= n && A[r] > A[largest]){
    largest = r;
  }
  if (largest != i){
    temp = A[i];
    A[i] = A[largest];
    A[largest] = temp;
    maxHeapify(largest);
  }
}
 
void buildMaxHeap(){
  int i;
  for( i = n/2;i>0;i--){
    maxHeapify(i);
  }
}
 
void maxHeapInsert(int key){
    n = n + 1;
    A[n] = INT_MIN;
    heapIncreaseKey(n,key);
}
 
 
void heapIncreaseKey(int i,int key){
  int tmp;
  if (key < A[i]){
    return;
  }
  A[i] = key;
  while (i > 1 && A[parent(i)] < A[i]){
    tmp = A[i];
    A[i] = A[parent(i)];
    A[parent(i)]= tmp;
    i = parent(i);
  }
}
 
int heapExtractMax(){
  int max;
  if ( n < 1){
    return;
  }
  max = A[1];
  A[1] = A[n];
  n = n - 1;
  maxHeapify(1);
  return max;
}
 
 
int main(){
  int takahiro;
  char sekine[10];
  while(1){
    scanf("%s",sekine);
    if(sekine[2]=='s'){
      scanf("%d",&takahiro);
      maxHeapInsert(takahiro);
    }
    if(sekine[2]=='t'){
      printf("%d\n",heapExtractMax());
    }
    if(sekine[2]=='d'){
      break;
    }
  }
    return 0;
}