a single vertex can appear once or twice . ch graphs might have only outgoing or only incoming edges . avoid double-counting . this is very inefficient . concode_field_sep int INITIAL_EDGELIST_CAPACITY concode_elem_sep IdentityHashMap<Vertex,List<Edge>> outgoing concode_elem_sep IdentityHashMap<Vertex,List<Edge>> incoming concode_elem_sep long serialVersionUID concode_field_sep boolean containsVertex concode_elem_sep int getDegreeOut concode_elem_sep List<Edge> getOutgoing concode_elem_sep void removeVertex concode_elem_sep void writeObject concode_elem_sep int countEdges concode_elem_sep void addIncoming concode_elem_sep void removeEdge concode_elem_sep void removeOutgoing concode_elem_sep void removeIncoming concode_elem_sep void addOutgoing concode_elem_sep Collection<Vertex> getVertices concode_elem_sep int getDegreeIn concode_elem_sep void addEdge concode_elem_sep List<Edge> getIncoming
int function ( ) { return getVertices ( ) . size ( ) ; }