void biconnectivity::init_handler(graph& G)
{
if (add_edges) {
dfs D;
D.scan_whole_graph(true);
D.check(G);
D.run(G);
roots_iterator it, end;
it = D.roots_begin();
end = D.roots_end();
start = *(*it);
++it;
for (; it != end; ++it) {
additional.push_back(G.new_edge(start, *(*it)));
}
first_child.init(G, node());
}
low_num.init(G);
in_component.init(G);
cut_count.init(G, 0);
//
// Detect self loops and hide them.
//
assert(self_loops.empty());
graph::edge_iterator eit = G.edges_begin(),
eend = G.edges_end();
while (eit != eend) {
edge e = *eit;
eit++;
if (e.target() == e.source()) {
self_loops.push_back(e);
G.hide_edge(e);
}
}
}
void biconnectivity::after_recursive_call_handler(graph& G, edge& e, node& n)
{
node curr = n.opposite(e);
if (low_num[n] < low_num[curr]) {
low_num[curr] = low_num[n];
}
if (low_num[n] >= dfs_num(curr)) {
//
// Component found
//
if (store_comp) {
component_iterator li = components.insert(
components.end(),
std::pair<nodes_t, edges_t>(nodes_t(), edges_t()));
nodes_t& component = li->first;
edges_t& co_edges = li->second;
//
// Nodes of biconnected component
//
node tmp = node_stack.top();
while (dfs_num(tmp) >= dfs_num(n)) {
node_stack.pop();
component.push_back(tmp);
in_component[tmp] = li;
if (node_stack.empty()) break;
else tmp = node_stack.top();
}
component.push_back(curr);
//
// edges of biconnected component
//
edge ed = edge_stack.top();
while ((dfs_num(ed.source()) >= dfs_num(n) &&
dfs_num(ed.target()) >= dfs_num(n)) ||
(dfs_num(ed.source()) == dfs_num(curr) &&
dfs_num(ed.target()) >= dfs_num(n)) ||
(dfs_num(ed.source()) >= dfs_num(n) &&
dfs_num(ed.target()) == dfs_num(curr))) {
edge_stack.pop();
co_edges.push_back(ed);
if (edge_stack.empty()) break;
else ed = edge_stack.top();
}
}
++num_of_components;
//
// curr is cut point; increase counter
//
++cut_count[curr];
if (add_edges) {
node father = (*preds)[curr];
node first = first_child[curr];
if (father != node() && n == first) {
additional.push_back(G.new_edge(father, first));
}
if (n != first) {
additional.push_back(G.new_edge(n, first));
}
}
}
}
