public Graph(int numV)
{
this.numV = numV;
this.adj = new List<List<Node>> ();
this.rAdj = new List<List<Node>> ();
for (int i = 0; i < numV; ++i)
{
List<Node> adjList = new List<Node> ();
this.adj.Add (adjList);
List<Node> rAdjList = new List<Node> ();
this.rAdj.Add (rAdjList);
}
}