heap

void (int* arr, int n){
  for(int pos = n / 2 - 1; pos >= 0; -- pos){
  	AjustHeap(arr, pos, n);
  }
  while(n > 0){
  	swap(arr[0], arr[n - 1]);
  	AjustHeap(arr, 0, n - 1);
  	-- n;
  }
}

void AjustHeap(int* arr, int node, int n){
  int left = node * 2 + 1;
  int right = node * 2 + 2;
  int max_pos = node;
  if (left < n && arr[left] > arr[max_pos]) max_pos = left;
  if (right < n && arr[right] > arr[max_pos]) max_pos = right;
  if (max_pos != node){
	swap(arr[max_pos], arr[node]);
	AjustHeap(arr, max_pos, n);
  }
}