@Test
public void testOffer() {

    System.out.println("offer");
    KMinValues instance = new KMinValues(20);
    
    System.out.println("Approx.\tReal");
    for (int i=0; i<100; i++) {
        instance.offer(String.valueOf(i));
        System.out.println(instance.cardinality() + "\t" + (i+1));
    }
}