SetUtil.java
import java.util.ArrayList;
import java.util.Set;
import java.util.TreeSet;
public class SetUtil
{
/**
Determine the strings that are unique to words1 and words2
@param words1 an array of strings
@param words2 an array of strings
@param a list of two sets: the words that are in words1 but not word2,
and the words that are in words2 but not word1. The sets should be sorted.
*/
public static List<Set<String>> uniqueInEach(String[] words1, String[] words2)
{
...
}
}