top.offerAll(ImmutableList.of("a", "B", "c", "D", "e", "F"));
    assertThat(top.topK()).containsExactly("a", "B", "c").inOrder();
  }

  public void testWorstCase() {
    int n = 2000000;
    int k = 200000;
    final long[] compareCalls = {0};
    Comparator<Integer> cmp =
        new Comparator<Integer>() {
          @Override
          public int compare(Integer o1, Integer o2) {