ArrayList<Integer> elements = new ArrayList<>(size);
    for (int i = 0; i < size; i++) {
      elements.add(i);
    }
    return elements;
  }

  public void testIsEvenLevel() {
    assertTrue(MinMaxPriorityQueue.isEvenLevel(0));
    assertFalse(MinMaxPriorityQueue.isEvenLevel(1));
    assertFalse(MinMaxPriorityQueue.isEvenLevel(2));
    assertTrue(MinMaxPriorityQueue.isEvenLevel(3));