Problem:
MathJax.Hub.Config({ tex2jax: { inlineMath: [["$","$"], ["\\(","\\)"]], processEscapes: true }});

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: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 500000
#define NIL -500000

int n;

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

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

int right(int i){
  return 2*i+1;
}
void heapIncreaseKey(int A[], int i, int key){
  int tmp;
  if (key < A[i]){
    return; //新しいキーは現在のキーより小さい
  }

  A[i] = key;
  while (i > 1 && A[parent(i)] < A[i]){
    tmp = A[i];
    A[i] = A[parent(i)];
    A[parent(i)] = tmp;
    i = parent(i);
  }
}

void maxHeapInsert(int A[], int key){
  n = n + 1;
  A[n] = NIL;
  heapIncreaseKey(A, n, key);
}



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

void BuildMaxHeap(int A[]){
  int i;
  for(i=n/2;i >= 1;i--){
    maxHeapify(A,i);
  }
}

int heapExtractMax(int A[]){
  int max;
  if(n < 1)
    return 0; //ヒープアンダーフロー
  max = A[1];
  A[1] = A[n];
  n = n - 1;
  maxHeapify(A, 1);
  return max;
}

main(){
  int i,x,a[N];
  char com[20];
  for( i = 1 ; i < N ; i++ ){
    scanf("%s",com);

    if(strcmp(com,"end")==0){
      break;
    }

    if(com[0]=='i'){
      scanf("%d",&x);
      maxHeapInsert(a,x);
    }

    else{
      printf("%d\n",heapExtractMax(a));
    }
  }
  return 0;
}