Hello, I am new to BGL, I was trying to test dijkstra_shortest_paths() with undirectedS, the result is not what I wanted, anyone giving help? Thanks, source code like dijkstra-example.cpp in the graph/example. int main(int, char *[]) { typedef adjacency_list < listS, vecS, undirectedS, no_property, property < edge_weight_t, double > > graph_t; typedef graph_traits < graph_t >::vertex_descriptor vertex_descriptor; typedef graph_traits < graph_t >::edge_descriptor edge_descriptor; typedef std::pair Edge; const int num_nodes = 3; Edge edge_array[] = { Edge(0, 1),Edge(1, 2), Edge(2, 0) }; double weights[] = {2.0, 1.0, 1.0}; int num_arcs = sizeof(edge_array) / sizeof(Edge);// #if defined(BOOST_MSVC) && BOOST_MSVC <= 1300 graph_t g(num_nodes); property_map::type weightmap = get (edge_weight, g); for (std::size_t j = 0; j < num_arcs; ++j) { edge_descriptor e; bool inserted; tie(e, inserted) = add_edge(edge_array[j].first, edge_array [j].second, g); weightmap[e] = weights[j]; } #else graph_t g(edge_array, edge_array + num_arcs, weights, num_nodes); property_map::type weightmap = get (edge_weight, g); #endif std::vector pred(num_vertices(g)); std::vector<double> d(num_vertices(g)); vertex_descriptor s = vertex(0, g); #if defined(BOOST_MSVC) && BOOST_MSVC <= 1300 // VC++ has trouble with the named parameters mechanism property_map::type indexmap = get (vertex_index, g); dijkstra_shortest_paths(g, s, &pred[0], &d[0], weightmap, indexmap, std::less<double>(), closed_plus<double>(), std::numeric_limits<double>::max(), 0, default_dijkstra_visitor()); #else dijkstra_shortest_paths(g, s, predecessor_map(&p[0]).distance_map(&d [0])); #endif std::cout << "distances and parents:" << std::endl; graph_traits < graph_t >::vertex_iterator vi, vend; for (tie(vi, vend) = vertices(g); vi != vend; ++vi) { std::cout << "distance(" << *vi << ") = " << d[*vi] << ", "; std::cout << "parent(" << *vi << ") = " << pred[*vi] << std::endl; } std::cout << "min paths tree" << std::endl; adjacency_list<> tree(num_nodes); for(tie(vi,vend) = vertices(g); vi != vend; ++vi) if (*vi != pred[*vi]) add_edge(pred[*vi], *vi, tree); print_graph(tree); std::cout << std::endl; return EXIT_SUCCESS; } The result is : distances and parents: distance(0) = 0, parent(0) = 0 distance(1) = 2, parent(1) = 0 distance(0) = 1, parent(2) = 0 min paths tree 0 -> 1 2 1 -> 2 -> I think the correct one should be: distances and parents: distance(0) = 0, parent(0) = 0 distance(1) = 2, parent(1) = 2 distance(2) = 1, parent(2) = 0 min paths tree 0 -> 1 1 -> 2 2 -> Any idea what is wrong? thanks!