@Test
    public void testDigraph2SingleLengthAncestor() {
        In in = new In("src\\tests\\data\\digraph2.txt");
        SAP sap = new SAP(new Digraph(in));
        assertTrue(sap.length(2, 3) == 1 && sap.ancestor(2, 3) == 3);
        assertTrue(sap.length(2, 5) == 3 && (sap.ancestor(2, 5) == 0 ||
                    sap.ancestor(2,5) == 5));
        assertTrue(sap.length(1, 5) == 2 && sap.ancestor(1, 5) == 0);
        assertTrue(sap.length(2, 3) == sap.length(3, 2));
        assertTrue(sap.length(2, 5) == sap.length(5, 2));
        assertTrue(sap.length(1, 5) == sap.length(5, 1));
    }