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 INF (1<<30)
int h=0;
void maxHeapify(int *Heap,int i){
  int l=2*i;
  int r=2*i+1;
  int largest;
  int tmp;
  if(l<=h && Heap[l]>Heap[i]) largest=l;
  else largest=i;
  if(r<=h && Heap[r]>Heap[largest]) largest = r;
  if(largest!=i){
    tmp=Heap[i];
    Heap[i]=Heap[largest];
    Heap[largest]=tmp;
    maxHeapify(Heap,largest);
  }
}
int insert(int x,int *Heap){
  int i,tmp;
  h++;
  Heap[h] =-INF;
  if(x<Heap[h]) return -1;
  Heap[h]=x;
  i=h;
  while(i>1&&Heap[i/2]<Heap[i]){
    tmp=Heap[i/2];
    Heap[i/2]=Heap[i];
    Heap[i]=tmp;
    i/=2;
  }
  return 0;
}
int extract(int *Heap){
  int maxv = Heap[1];
  if(h < 1) return -INF;
  Heap[1] = Heap[h];
  h--;
  maxHeapify(Heap,1);
  return maxv;
}    
int main(){
  int n;
  char s[20];
  int Heap[MAX+2];
  while(1){
    scanf("%s",s);
    if(s[0]=='e'&&s[1]=='n') break;
    if(s[0]=='i'){
      scanf("%d",&n);
      insert(n,Heap);
    }else{
      printf("%d\n",extract(Heap));
    }
  }
  return 0;
}