@Test
    public void testDigraph1SingleLengthAncestor() {
        In in = new In("src\\tests\\data\\digraph1.txt");
        SAP sap = new SAP(new Digraph(in));
        assertTrue(sap.length(9, 12) == 3 && sap.ancestor(9, 12) == 5);
        assertTrue(sap.length(9, 8) == 4 && sap.ancestor(9, 8) == 1);
        assertTrue(sap.length(9, 8) == sap.length(8, 9));
        assertTrue(sap.length(7, 12) == sap.length(12, 7));
    }