public static void TestGraph2()
        {
            FastChange fc = new FastChange();

            for (int i = 0; i < (int)Constant.tassi.LAST_VALUE; i++)
            {
                string[] entry = ((Constant.tassi)i).ToString().Split('_');
                fc.addString(entry[0]);
                fc.addString(entry[1]);
            }

            Digraph d = new Digraph(fc.numberOfItems);

            for (int i = 0; i < (int)Constant.tassi.LAST_VALUE; i++)
            {
                string[] entry = ((Constant.tassi)i).ToString().Split('_');
                d.addEdge(entry[0], entry[1]);
                d.addEdge(entry[1], entry[0]);
            }
        }
        public static void TestGraph()
        {
            Digraph d = new Digraph(7);

            d.addEdge(0, 1);
            d.addEdge(1, 2);
            d.addEdge(2, 3);
            d.addEdge(3, 1);
            d.addEdge(0, 4);
            d.addEdge(4, 5);
            d.addEdge(5, 6);
            d.addEdge(6, 0);

            DirectedCycle dc = new DirectedCycle(d);

            var list = dc.returnCycle();
        }