}

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

    assertFalse(MinMaxPriorityQueue.isEvenLevel((1 << 10) - 2));
    assertTrue(MinMaxPriorityQueue.isEvenLevel((1 << 10) - 1));

    int i = 1 << 29;

    removeAt(index);
    return value;
  }

  private Heap heapForIndex(int i) {
    return isEvenLevel(i) ? minHeap : maxHeap;
  }

  private static final int EVEN_POWERS_OF_TWO = 0x55555555;
  private static final int ODD_POWERS_OF_TWO = 0xaaaaaaaa;

  @VisibleForTesting
  static boolean isEvenLevel(int index) {
    int oneBased = ~~(index + 1); // for GWT
    checkState(oneBased > 0, "negative index");