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>

int p=0;
int q[2000001];

int max(int,int);
int extract();
void swap(int,int);
void insert(int);

int main(){
  char c[10];
  int i,j;
  int k;
  while(1){
    scanf("%s",c);
  
  if(c[0]=='i'){
      scanf("%d",&k);
      insert(k);
    }

    if(c[0]=='e'){

      if(c[1]=='x')
    printf("%d\n",extract());

      if(c[1]=='n') break;
    }
  }
  return 0;
}

int max(int a,int b){

  if(q[a]>q[b])return a;
  else return b;

}

void swap(int a,int b){
  int t;
  t=q[a];
  q[a]=q[b];
  q[b]=t;
}
 
void insert(int k){
  int t;
  int i,j;
  p++;
  q[p]=k;
  i=p;
  while(q[i]>q[i/2] && i>1){
    swap(i,i/2);
    i=i/2;
  }
}

int extract(){
  int r=q[1];
  int i;
  int t;
  int M;
  q[1]=q[p];
  p--;
  i=1;
  while(i*2 <= p ){
    if(i*2+1 <= p)
      M=max(i*2,i*2+1);
    else M=i*2;
    if(max(M,i)==M){swap(M,i);i=M;}
    else break;
     
  }
  return r;
}