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<limits.h>

#define MAX 2000000
#define N 2000000001

int T[MAX];

int n=0;

int parent(int i){
  return i/2;
}

int left(int i){
  return 2*i;
}

int right(int i){
  return 2*i+1;
}

void heapIncreaseKey(i, key){
  int x;
  if(key < T[i]) printf("new kry is smaller than current key");
  T[i] = key;
  while( i > 1 && T[parent(i)] < T[i]){
    x = T[i];
    T[i] = T[parent(i)];
    T[parent(i)] = x;
    i = parent(i);
  }
}

void maxHeapInsert(key){
  n++;
  T[n] = INT_MIN;
  heapIncreaseKey(n, key);
}

void maxHeapify(int i){
  int h, l, r, largest;
  l = left(i);
  r = right(i);
  if(l <= n && T[l] > T[i]) largest = l;
  else largest = i;
  if(r <= n && T[r] > T[largest]) largest = r;
  if(largest != i){
    h = T[i];
    T[i] = T[largest];
    T[largest] = h;
    maxHeapify(largest);
  }
}

int heapExtractMax(void){
  int max;
  if(n < 1) printf("heap underflow");;
  max = T[1];
  T[1] = T[n];
  n--;
  maxHeapify(1);
  return max;
}

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

int main(){
  int i=1, k=0, j;
  char com[10];
  int p[MAX];

  while(1){
    scanf("%s", com);
    if(com[2] == 's'){
      scanf("%d", &T[i]);
      maxHeapInsert(T[i]);
      i++;
    }
    else if(com[2] == 't'){
      p[k] = heapExtractMax();
      k++;
    }
    else if(com[2] == 'd'){
      for(i=0; i<k; i++) printf("%d\n",p[i]);
      break;
    }
  }
  return 0;
}