private void DFSVisit(Knoten2 v, int index, string zyklus)
        {
            int i;

            time       += 1;
            v.firstTime = time;
            v.color     = "grau";

            for (i = 0; i < matrix.GetLength(1); i++)
            {
                if (matrix[index, i] == 1)
                {
                    if (knoten[i].color == "weiß")
                    {
                        knoten[i].pred = v;
                        DFSVisit(knoten[i], i, zyklus + i + " - ");
                    }
                    else if (knoten[i].color == "grau" && knoten[i] != v && knoten[i] != v.pred)
                    {
                        zyklus += Array.IndexOf(knoten, knoten[i]);
                        int test = Array.IndexOf(knoten, knoten[i]);
                        zyklus = zyklus.Substring(zyklus.IndexOf(test.ToString()));
                        Console.WriteLine("Zyklus gefunden: " + zyklus);
                        break;
                    }
                }
            }

            v.color    = "schwarz";
            time      += 1;
            v.lastTime = time;
            // Console.Write(index + " ");
        }
        public void DFS()
        {
            int i;

            Console.Write("Tiefensuche: ");

            for (i = 0; i < knoten.Length; i++)
            {
                knoten[i]       = new Knoten2();
                knoten[i].color = "weiß";
                knoten[i].pred  = null;
            }

            for (i = 0; i < 1; i++)
            {
                if (knoten[i].color == "weiß")
                {
                    DFSVisit(knoten[i], i, (i + " - "));
                }
            }

            Console.WriteLine();
        }