<HTML>
<!-- Copyright 2007 Aaron Windsor
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt)
-->
<Head>
<Title>Boost Graph Library: make_connected</Title>
<BODY BGCOLOR="#ffffff" LINK="#0000ee" TEXT="#000000" VLINK="#551a8b"
ALINK="#ff0000">
<IMG SRC="../../../boost.png"
ALT="C++ Boost" width="277" height="86">
<BR Clear>
<H1><tt>make_connected</tt></H1>
<p>
<pre>
template <typename Graph, typename VertexIndexMap, typename AddEdgeVisitor>
make_connected(Graph& g, VertexIndexMap vm, AddEdgeVisitor& vis);
</pre>
<p>
A undirected graph <i>G</i> is connected if, for every pair of vertices
<i>u,v</i> in <i>G</i>, there is a path from <i>u</i> to <i>v</i>.
<tt>make_connected</tt> adds the minimum number of edges needed to make the
input graph connected. The algorithm first identifies all of the
<a href="./connected_components.html">connected components</a> in the graph,
then adds edges to connect those components together in a path. For example, if
a graph contains three connected components <i>A</i>, <i>B</i>, and <i>C</i>,
<tt>make_connected</tt> will add two edges. The two edges added might consist
of one connecting a vertex in <i>A</i> with a vertex in <i>B</i> and one
connecting a vertex in <i>B</i> with a vertex in <i>C</i>.
<p>
The default behavior of <tt>make_connected</tt> is to modify the graph
<tt>g</tt> by calling <tt>add_edge(u,v,g)</tt> for every pair of vertices
<i>(u,v)</i> where an edge needs to be added to connect <tt>g</tt>. This
behavior can be overriden by providing a vistor as the <tt>AddEdgeVisitor</tt>
parameter. The only requirement for an <tt>AddEdgeVisitor</tt> is that it
define a member function with the following signature:
<pre>
template <typename Graph, typename Vertex>
void visit_vertex_pair(Vertex u, Vertex v, Graph& g);
</pre>
This event point can also be used as a hook to update the underlying edge
index map automatically as edges are added. See the
documentation for the <a href="./AddEdgeVisitor.html">AddEdgeVisitor</a>
concept for more information.
<H3>Where Defined</H3>
<P>
<a href="../../../boost/graph/make_connected.hpp">
<TT>boost/graph/make_connected.hpp</TT>
</a>
<h3>Parameters</h3>
IN/OUT: <tt>Graph& g</tt>
<blockquote>
An undirected graph. The graph type must be a model of <a
href="VertexListGraph.html">Vertex List Graph</a>, <a
href="IncidenceGraph.html">Incidence Graph</a>, and
a <a href="MutableGraph.html">Mutable Graph</a><br>
</blockquote>
IN: <tt>VertexIndexMap vm</tt>
<blockquote>
A <a href="../../property_map/doc/ReadablePropertyMap.html">Readable Property Map
</a> that maps vertices from <tt>g</tt> to distinct integers in the range
<tt>[0, num_vertices(g) )</tt><br>
<b>Default</b>: <tt>get(vertex_index,g)</tt><br>
</blockquote>
IN: <tt>AddEdgeVisitor</tt>
<blockquote>
A model of <a href="AddEdgeVisitor.html">AddEdgeVisitor
</a>.<br>
<b>Default</b>: <tt>default_add_edge_visitor</tt>, a class defines
<tt>visit_vertex_pair</tt> to dispatch
its calls to <tt>add_edge</tt>.
</blockquote>
<h3>Complexity</h3>
On a graph with <i>n</i> vertices and <i>m</i> edges, <tt>make_connected</tt>
runs in time <i>O(n + m)</i>
<H3>Example</H3>
<P>
<a href="../example/make_connected.cpp">
<TT>../example/make_connected.cpp</TT>
</a>
<h3>See Also</h3>
<a href="planar_graphs.html">Planar Graphs in the Boost Graph Library</a>
<br>
<HR>
Copyright © 2007 Aaron Windsor (<a href="mailto:aaron.windsor@gmail.com">
aaron.windsor@gmail.com</a>)
</BODY>
</HTML>
