/* ==========================================
* 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 2003-2008, by Barak Naveh and Contributors.
*
* This program and the accompanying materials are dual-licensed under
* either
*
* (a) the terms of the GNU Lesser General Public License version 2.1
* as published by the Free Software Foundation, or (at your option) any
* later version.
*
* or (per the licensee's choosing)
*
* (b) the terms of the Eclipse Public License v1.0 as published by
* the Eclipse Foundation.
*/
/* -------------------------
* BiconnectivityInspector.java
* -------------------------
* (C) Copyright 2007-2008, by France Telecom
*
* Original Author: Guillaume Boulmier and Contributors.
* Contributor(s): John V. Sichi
*
* $Id$
*
* 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<V, E>
{
private BlockCutpointGraph<V, E> blockCutpointGraph;
/**
* Running time = O(m) where m is the number of edges.
*/
public BiconnectivityInspector(UndirectedGraph<V, E> graph)
{
super();
this.blockCutpointGraph = new BlockCutpointGraph<V, E>(graph);
}
/**
* Returns the biconnected vertex-components of the graph.
*/
public Set<Set<V>> getBiconnectedVertexComponents()
{
Set<Set<V>> biconnectedVertexComponents = new HashSet<Set<V>>();
for (
Iterator<UndirectedGraph<V, E>> iter =
this.blockCutpointGraph.vertexSet().iterator();
iter.hasNext();)
{
UndirectedGraph<V, E> 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<Set<V>> getBiconnectedVertexComponents(V vertex)
{
Set<Set<V>> vertexComponents = new HashSet<Set<V>>();
for (
Iterator<Set<V>> iter = getBiconnectedVertexComponents().iterator();
iter.hasNext();)
{
Set<V> vertexComponent = iter.next();
if (vertexComponent.contains(vertex)) {
vertexComponents.add(vertexComponent);
}
}
return vertexComponents;
}
/**
* Returns the cutpoints of the graph.
*/
public Set<V> getCutpoints()
{
return this.blockCutpointGraph.getCutpoints();
}
/**
* Returns <code>true</code> if the graph is biconnected (no cutpoint),
* <code>false</code> otherwise.
*/
public boolean isBiconnected()
{
return this.blockCutpointGraph.vertexSet().size() == 1;
}
}
// End BiconnectivityInspector.java