class DirectedGraph{

public:

  addVertex(v, ...)
  addEdge(src, dst, ..)

  remove

  containsEdge(src, dst)
  containsVertex(v)

  getInNeighbors(vertex)
  getOutNeighbors(vertex)

  getInEdges(vertex)
  getOutEdges(vertex)

  isConnected(v1, v2)
  getPath(v1, v2)

  getVertices()
  getEdges()
}


template V
class SimpleGraph : DirectedGraph{

private:

  vector<V> vertices;
  vector< pair<V,V> > edges;

}


template V
class AdjacencyListGraph: DirectedGraph{

private:

  vector<V> vertices;
  vector< vector< pair<V,V> > > edges;

}