#define PARALLEL_GRAPH

using namespace boost;

using boost::graph::distributed::mpi_process_group;

typedef adjacency_list <vecS, vecS, undirectedS> SerialGraph;

typedef adjacency_list<vecS, distributedS<mpi_process_group, vecS>, undirectedS> Graph;

typedef iterator_property_map<std::vector<int>::iterator, property_map<Graph, vertex_index_t>::type> LocalMap;

static char help[] = "";

int main(int argc,char **args)

{

    PetscErrorCode ierr;

PetscInitialize(&argc,&args,(char*)0,help);

    int nV = 40000;

    int num = 0;

#ifdef PARALLEL_GRAPH

    Graph G(nV+1);

    synchronize(G);

    std::vector<int> localComponent(nV+1);

    LocalMap components(localComponent.begin(),get(vertex_index, G));

    num = connected_components_ps(G, components);

#else

    SerialGraph G(nV+1);

    std::vector<int> globalComponent(nV+1);

    num = connected_components(G, &globalComponent[0]);

#endif

    std::cout << num << " connected components" << std::endl;

ierr = PetscFinalize();

return 0;

}