import java.util.Arrays;
import java.util.BitSet;
import org.apache.commons.lang3.ArrayUtils;

public class OrderDisjointItems {

    public static void main(String[] args) {
        final String[][] MNs = {{"the cat sat on the mat", "mat cat"},
        {"the cat sat on the mat", "cat mat"},
        {"A B C A B C A B C", "C A C A"}, {"A B C A B D A B E", "E A D A"},
        {"A B", "B"}, {"A B", "B A"}, {"A B B A", "B A"}, {"X X Y", "X"}};

        for (String[] a : MNs) {
            String[] r = orderDisjointItems(a[0].split(" "), a[1].split(" "));
            System.out.printf("%s |%s ->%s%n", a[0], a[1], Arrays.toString(r));
        }
    }