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 SIZE 2000000

int A[SIZE];
int H;

void insert(int x)
{
  int tmp;
  A[H] = x;
  H++;
  int i=H-1;
  int parent = (i-1)/2;
  if (H<1) return;
  while (A[parent]<A[i]) {
    tmp = A[parent];
    A[parent] = A[i];
    A[i] = tmp;
    if (i==0) break;
    tmp = i;
    i = parent;
    parent = (i-1)/2;
  }
}

void maxHeapify(int i) {
  int largest, tmp;
  int l = (i+1)*2-1;
  int r = (i+1)*2;

  if (l<H && A[l]>A[i])      largest = l;
  else                       largest = i;
  if (r<H && A[r]>A[largest])  largest = r;

  if (largest != i) {
    tmp = A[i];
    A[i] = A[largest];
    A[largest] = tmp;
    maxHeapify(largest);
  }
}
int extract()
{
  if (H<0) return -1;
  int val = A[0];
  A[0]=A[H-1];
  maxHeapify(0);
  H--;
  return val;
}


void print()
{
  int i, n=1;
  printf("[ ");
  while (1) {
    for (i=n-1; i<=(n-1)*2; i++) {
      if (i>=H) goto END;
      printf("%d ",A[i]);
    }
    printf("\n");
    n*=2;
  }
 END:
  printf("] H==%d\n", H);
}

int main() {
  int key;
  char com[20];
  while (1) {
    scanf("%s", com);
    if (com[2] == 'd')   break;
    if (com[0] == 'i') {
      scanf("%u", &key);
      insert(key);
    } else { // extract
      int e = extract();
      if (e<0) break;
      printf("%d\n", e);
    }
  }
  return 0;
}