private void updateHeap(int i) {
        int left = 2 * i+1;
        int right = 2 * i + 2;
        int max = i;
        if (left < size && vector[left] > vector[i]) {
            max = left;
        }
        if (right < size && vector[right] > vector[max]) {
            max = right;
        }
        if (max != i) {
            swap(vector, i, max);
            updateHeap(max);
        }
    }