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 <stdlib.h>
#include <string.h>
int n=0;

void maxHeapify(int node[],int i){
  int l =2*i;
  int r = 2*i+1;
  int largest;
  int temp;

  if(l <= n && node[l] > node[i]){
    largest =l;
  }
  else{
    largest = i;
  }
  if(r <= n && node[r] > node[largest]){
    largest = r; 
  }
  if(largest != i){
    temp = node[i];
    node[i] = node[largest];
    node[largest] = temp;
    maxHeapify(node,largest);
  }
}

void buildMaxHeap(int node[]){
  int i;
  for(i=n/2;i>0;i--){
    maxHeapify(node,i);
  }
}

void heapIncreaseKey(int node[],int i,int k){
  int temp;
  if(k < node[i]){
    fprintf(stderr,"error\n");
  }
  node[i] = k;
  while(i >1 && node[i/2] < node[i]){
    temp = node[i];
    node[i] = node[i/2];
    node[i/2] = temp;
    i = i/2;
  }
}


void heapInsert(int node[],int k){
  n = n+1;
  node[n] = -10000000;
  heapIncreaseKey(node,n,k);
}

int heapExtractMax(int node[]){
  int max;
  if(n < 1){
    fprintf(stderr,"error\n");
  }
  max = node[1];
  node[1] = node[n];
  n = n-1;
  maxHeapify(node,1);
  return max;
}

int main(){
  int i,k,node[2000000];
  char s[20];

  while(1){
    scanf("%s",s);
    if(strcmp(s,"insert") == 0){
      scanf("%d",&k);
      heapInsert(node,k);
    }
    else if(strcmp(s,"extract") == 0){
      printf("%d\n",heapExtractMax(node));
    }
    else if(strcmp(s,"end")== 0){
      break;
    }
  }
  return 0;
}