int main()
{
// Construct an arrangement of seven intersecting line segments.
Point_2 p1(1, 1), p2(1, 4), p3(2, 2), p4(3, 7), p5(4, 4), p6(7, 1), p7(9, 3);
Ex_arrangement arr;
insert(arr, Segment_2(p1, p6));
insert(arr, Segment_2(p1, p4)); insert(arr, Segment_2(p2, p6));
insert(arr, Segment_2(p3, p7)); insert(arr, Segment_2(p3, p5));
insert(arr, Segment_2(p6, p7)); insert(arr, Segment_2(p4, p7));
// Create a mapping of the arrangement faces to indices.
Face_index_map index_map(arr);
// Perform breadth-first search from the unbounded face, using the event
// visitor to associate each arrangement face with its discover time.
unsigned int time = 0;
boost::breadth_first_search(Dual_arrangement(arr), arr.unbounded_face(),
boost::vertex_index_map(index_map).visitor
(boost::make_bfs_visitor
(stamp_times(Face_property_map(), time,
boost::on_discover_vertex()))));
// Print the discover time of each arrangement face.
Ex_arrangement::Face_iterator fit;
for (fit = arr.faces_begin(); fit != arr.faces_end(); ++fit) {
std::cout << "Discover time " << fit->data() << " for ";
if (fit != arr.unbounded_face()) {
std::cout << "face ";
print_ccb<Ex_arrangement>(fit->outer_ccb());
}
else std::cout << "the unbounded face." << std::endl;
}
return 0;
}
typename property_traits<ComponentsMap>::value_type
kosaraju_strong_components(Graph& G, ComponentsMap c,
FinishTime finish_time, ColorMap color)
{
function_requires< MutableGraphConcept<Graph> >();
// ...
typedef typename graph_traits<Graph>::vertex_descriptor Vertex;
typedef typename property_traits<ColorMap>::value_type ColorValue;
typedef color_traits<ColorValue> Color;
typename property_traits<FinishTime>::value_type time = 0;
depth_first_search
(G, make_dfs_visitor(stamp_times(finish_time, time, on_finish_vertex())),
color);
Graph G_T(num_vertices(G));
transpose_graph(G, G_T);
typedef typename property_traits<ComponentsMap>::value_type count_type;
count_type c_count(0);
detail::components_recorder<ComponentsMap>
vis(c, c_count);
// initialize G_T
typename graph_traits<Graph>::vertex_iterator ui, ui_end;
for (tie(ui, ui_end) = vertices(G_T); ui != ui_end; ++ui)
put(color, *ui, Color::white());
typedef typename property_traits<FinishTime>::value_type D;
typedef indirect_cmp< FinishTime, std::less<D> > Compare;
Compare fl(finish_time);
std::priority_queue<Vertex, std::vector<Vertex>, Compare > Q(fl);
typename graph_traits<Graph>::vertex_iterator i, j, iend, jend;
tie(i, iend) = vertices(G_T);
tie(j, jend) = vertices(G);
for ( ; i != iend; ++i, ++j) {
put(finish_time, *i, get(finish_time, *j));
Q.push(*i);
}
while ( !Q.empty() ) {
Vertex u = Q.top();
Q.pop();
if (get(color, u) == Color::white()) {
depth_first_visit(G_T, u, vis, color);
++c_count;
}
}
return c_count;
}
