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JGraphT is a free Java graph library
that provides mathematical graph-theory objects and algorithms
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/* ==========================================
* JGraphT : a free Java graph-theory library
* ==========================================
*
* Project Info: http://jgrapht.sourceforge.net/
* Project Creator: Barak Naveh (http://sourceforge.net/users/barak_naveh)
*
* (C) Copyright 2003-2007, by Barak Naveh and Contributors.
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this library; if not, write to the Free Software Foundation,
* Inc.,
* 59 Temple Place, Suite 330, Boston, MA 02111-1307, USA.
*/
/* -------------------------
* BiconnectivityInspector.java
* -------------------------
* (C) Copyright 2007-2007, by France Telecom
*
* Original Author: Guillaume Boulmier and Contributors.
* Contributor(s): John V. Sichi
*
* $Id: BiconnectivityInspector.java 568 2007-09-30 00:12:18Z perfecthash $
*
* Changes
* -------
* 05-Jun-2007 : Initial revision (GB);
* 05-Jul-2007 : Added support for generics (JVS);
*
*/
package org.jgrapht.alg;
import java.util.*;
import org.jgrapht.*;
/**
* Inspects a graph for the biconnectivity property. See {@link
* BlockCutpointGraph} for more information. A biconnected graph has only one
* block (i.e. no cutpoints).
*
* @author Guillaume Boulmier
* @since July 5, 2007
*/
public class BiconnectivityInspector
{
//~ Instance fields --------------------------------------------------------
private BlockCutpointGraph blockCutpointGraph;
//~ Constructors -----------------------------------------------------------
/**
* Running time = O(m) where m is the number of edges.
*/
public BiconnectivityInspector(UndirectedGraph graph)
{
super();
this.blockCutpointGraph = new BlockCutpointGraph(graph);
}
//~ Methods ----------------------------------------------------------------
/**
* Returns the biconnected vertex-components of the graph.
*/
public Set> getBiconnectedVertexComponents()
{
Set> biconnectedVertexComponents = new HashSet>();
for (
Iterator> iter =
this.blockCutpointGraph.vertexSet().iterator();
iter.hasNext();)
{
UndirectedGraph subgraph = iter.next();
if (!subgraph.edgeSet().isEmpty()) {
biconnectedVertexComponents.add(subgraph.vertexSet());
}
}
return biconnectedVertexComponents;
}
/**
* Returns the biconnected vertex-components containing the vertex. A
* biconnected vertex-component contains all the vertices in the component.
* A vertex which is not a cutpoint is contained in exactly one component. A
* cutpoint is contained is at least 2 components.
*
* @param vertex
*
* @return set of all biconnected vertex-components containing the vertex.
*/
public Set> getBiconnectedVertexComponents(V vertex)
{
Set> vertexComponents = new HashSet>();
for (
Iterator> iter = getBiconnectedVertexComponents().iterator();
iter.hasNext();)
{
Set vertexComponent = iter.next();
if (vertexComponent.contains(vertex)) {
vertexComponents.add(vertexComponent);
}
}
return vertexComponents;
}
/**
* Returns the cutpoints of the graph.
*/
public Set getCutpoints()
{
return this.blockCutpointGraph.getCutpoints();
}
/**
* Returns true if the graph is biconnected (no cutpoint),
* false otherwise.
*/
public boolean isBiconnected()
{
return this.blockCutpointGraph.vertexSet().size() == 1;
}
}
// End BiconnectivityInspector.java