/* ==========================================
* 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 2003-2011, 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.
*/
/* ----------------
* StoerWagnerMinimumCutTest.java
* ----------------
* (C) Copyright 2011-2011, by Robby McKilliam and Contributors.
*
* Original Author: Robby McKilliam
* Contributor(s): -
*
* $Id: StoerWagnerMinimumCut.java $
*
* Changes
* -------
*
*/
package org.jgrapht.alg;
import java.util.*;
import junit.framework.*;
import org.jgrapht.graph.*;
/**
* @author Robby McKilliam
*/
public class StoerWagnerMinimumCutTest
extends TestCase
{
//~ Instance fields --------------------------------------------------------
private String v1 = "v1";
private String v2 = "v2";
private String v3 = "v3";
private String v4 = "v4";
private String v5 = "v5";
private String v6 = "v6";
private String v7 = "v7";
private String v8 = "v8";
//~ Constructors -----------------------------------------------------------
public StoerWagnerMinimumCutTest()
{
}
//~ Methods ----------------------------------------------------------------
/**
* Test of mergeVertices method, of class StoerWagnerMinimumCut.
*/
public void testMinCut14()
{
SimpleWeightedGraph<String, DefaultWeightedEdge> g =
new SimpleWeightedGraph<String, DefaultWeightedEdge>(
DefaultWeightedEdge.class);
g.addVertex(v1);
g.addVertex(v2);
g.addVertex(v3);
g.addVertex(v4);
DefaultWeightedEdge e;
e = g.addEdge(v1, v2);
g.setEdgeWeight(e, 3.0);
e = g.addEdge(v1, v3);
g.setEdgeWeight(e, 2.0);
e = g.addEdge(v1, v4);
g.setEdgeWeight(e, 4.0);
e = g.addEdge(v2, v3);
g.setEdgeWeight(e, 1.0);
e = g.addEdge(v3, v4);
g.setEdgeWeight(e, 1.0);
StoerWagnerMinimumCut<String, DefaultWeightedEdge> mincut =
new StoerWagnerMinimumCut<String, DefaultWeightedEdge>(g);
assertEquals(4.0, mincut.minCutWeight(), 0.000001);
}
/**
* Test of mergeVertices method, of class StoerWagnerMinimumCut.
*/
public void testMinCutDisconnected()
{
SimpleWeightedGraph<String, DefaultWeightedEdge> g =
new SimpleWeightedGraph<String, DefaultWeightedEdge>(
DefaultWeightedEdge.class);
g.addVertex(v1);
g.addVertex(v2);
g.addVertex(v3);
g.addVertex(v4);
DefaultWeightedEdge e;
e = g.addEdge(v1, v2);
g.setEdgeWeight(e, 3.0);
e = g.addEdge(v1, v3);
g.setEdgeWeight(e, 2.0);
e = g.addEdge(v2, v3);
g.setEdgeWeight(e, 1.0);
StoerWagnerMinimumCut<String, DefaultWeightedEdge> mincut =
new StoerWagnerMinimumCut<String, DefaultWeightedEdge>(g);
assertEquals(0.0, mincut.minCutWeight(), 0.000001);
}
/**
* Test of StoerWagnerMinimumCut when a 0-weight edge exists.
*/
public void testMinCut0Weight()
{
SimpleWeightedGraph<String, DefaultWeightedEdge> g =
new SimpleWeightedGraph<String, DefaultWeightedEdge>(
DefaultWeightedEdge.class);
g.addVertex(v1);
g.addVertex(v2);
g.addVertex(v3);
g.addVertex(v4);
g.addVertex(v5);
g.addVertex(v6);
g.addVertex(v7);
g.addVertex(v8);
DefaultWeightedEdge e;
e = g.addEdge(v1, v2); g.setEdgeWeight(e, 1.0);
e = g.addEdge(v2, v3); g.setEdgeWeight(e, 2.0);
e = g.addEdge(v3, v4); g.setEdgeWeight(e, 0.0);
e = g.addEdge(v4, v5); g.setEdgeWeight(e, 1.0);
e = g.addEdge(v5, v6); g.setEdgeWeight(e, 2.0);
e = g.addEdge(v6, v1); g.setEdgeWeight(e, 0.0);
e = g.addEdge(v6, v8); g.setEdgeWeight(e, 1.0);
e = g.addEdge(v8, v7); g.setEdgeWeight(e, 0.0);
e = g.addEdge(v7, v3); g.setEdgeWeight(e, 2.0);
StoerWagnerMinimumCut<String, DefaultWeightedEdge> mincut =
new StoerWagnerMinimumCut<String, DefaultWeightedEdge>(g);
Set<String> solution1 = new HashSet<String>();
Collections.addAll(solution1, v4, v5, v6, v8);
Set<String> solution2 = new HashSet<String>();
Collections.addAll(solution2, v1, v2, v3, v7);
assertEquals(0.0, mincut.minCutWeight(), 0.000001);
assertTrue(mincut.minCut().equals(solution1) ||
mincut.minCut().equals(solution2) );
}
/**
* Test of StoerWagnerMinimumCut when a <1-weight edge exists.
*/
public void testMinCutSmallWeight()
{
SimpleWeightedGraph<String, DefaultWeightedEdge> g =
new SimpleWeightedGraph<String, DefaultWeightedEdge>(
DefaultWeightedEdge.class);
g.addVertex(v1);
g.addVertex(v2);
g.addVertex(v3);
g.addVertex(v4);
DefaultWeightedEdge e;
e = g.addEdge(v1, v2); g.setEdgeWeight(e, 0.5);
e = g.addEdge(v2, v3); g.setEdgeWeight(e, 1.0);
e = g.addEdge(v3, v4); g.setEdgeWeight(e, 0.5);
e = g.addEdge(v4, v1); g.setEdgeWeight(e, 1.0);
StoerWagnerMinimumCut<String, DefaultWeightedEdge> mincut =
new StoerWagnerMinimumCut<String, DefaultWeightedEdge>(g);
Set<String> solution1 = new HashSet<String>();
Collections.addAll(solution1, v1, v4);
Set<String> solution2 = new HashSet<String>();
Collections.addAll(solution2, v2, v3);
assertEquals(1.0, mincut.minCutWeight(), 0.000001);
assertTrue(mincut.minCut().equals(solution1) ||
mincut.minCut().equals(solution2) );
}
/**
* Test of StoerWagnerMinimumCut on a Multigraph.
*/
public void testMinCutMultigraph()
{
WeightedMultigraph<String, DefaultWeightedEdge> g =
new WeightedMultigraph<String, DefaultWeightedEdge>(
DefaultWeightedEdge.class);
g.addVertex(v1);
g.addVertex(v2);
g.addVertex(v3);
DefaultWeightedEdge e;
e = g.addEdge(v1, v2); g.setEdgeWeight(e, 1.5);
e = g.addEdge(v1, v2); g.setEdgeWeight(e, 1.5);
e = g.addEdge(v2, v3); g.setEdgeWeight(e, 2.0);
StoerWagnerMinimumCut<String, DefaultWeightedEdge> mincut =
new StoerWagnerMinimumCut<String, DefaultWeightedEdge>(g);
Set<String> solution1 = new HashSet<String>();
Collections.addAll(solution1, v1, v2);
Set<String> solution2 = new HashSet<String>();
Collections.addAll(solution2, v3);
assertEquals(2.0, mincut.minCutWeight(), 0.000001);
assertTrue(mincut.minCut().equals(solution1) ||
mincut.minCut().equals(solution2) );
}
/**
* Test of StoerWagnerMinimumCut on an unweighted graph
*/
public void testMinCutUnweighted()
{
SimpleGraph<String, DefaultEdge> g =
new SimpleGraph<String, DefaultEdge>(DefaultEdge.class);
g.addVertex(v1);
g.addVertex(v2);
g.addVertex(v3);
g.addVertex(v4);
g.addVertex(v5);
g.addVertex(v6);
DefaultEdge e;
e = g.addEdge(v1, v2);
e = g.addEdge(v2, v3);
e = g.addEdge(v3, v1);
e = g.addEdge(v4, v5);
e = g.addEdge(v5, v6);
e = g.addEdge(v6, v4);
e = g.addEdge(v3, v4);
StoerWagnerMinimumCut<String, DefaultEdge> mincut =
new StoerWagnerMinimumCut<String, DefaultEdge>(g);
Set<String> solution1 = new HashSet<String>();
Collections.addAll(solution1, v1, v2, v3);
Set<String> solution2 = new HashSet<String>();
Collections.addAll(solution2, v4, v5, v6);
assertEquals(1.0, mincut.minCutWeight(), 0.000001);
assertTrue(mincut.minCut().equals(solution1) ||
mincut.minCut().equals(solution2) );
}
/**
* Test of StoerWagnerMinimumCut on empty and small graphs
*/
public void testMinCutEmpty()
{
SimpleGraph<String, DefaultEdge> g =
new SimpleGraph<String, DefaultEdge>(DefaultEdge.class);
StoerWagnerMinimumCut<String, DefaultEdge> mincut;
boolean caught = false;
// No vertices
try {
mincut = new StoerWagnerMinimumCut<String, DefaultEdge>(g);
} catch (IllegalArgumentException ex) {
caught = true;
}
assertTrue(caught);
}
/**
* Test of StoerWagnerMinimumCut on empty and small graphs
*/
public void testMinCutSingleton()
{
SimpleGraph<String, DefaultEdge> g =
new SimpleGraph<String, DefaultEdge>(DefaultEdge.class);
StoerWagnerMinimumCut<String, DefaultEdge> mincut;
boolean caught = false;
// 1 vertex
caught = false;
g.addVertex(v1);
try {
mincut = new StoerWagnerMinimumCut<String, DefaultEdge>(g);
} catch (IllegalArgumentException ex) {
caught = true;
}
assertTrue(caught);
}
/**
* Test of StoerWagnerMinimumCut on empty and small graphs
*/
public void testMinCutDoubleton()
{
SimpleGraph<String, DefaultEdge> g =
new SimpleGraph<String, DefaultEdge>(DefaultEdge.class);
StoerWagnerMinimumCut<String, DefaultEdge> mincut;
// 2 vertices, no edges
g.addVertex(v1);
g.addVertex(v2);
mincut = new StoerWagnerMinimumCut<String, DefaultEdge>(g);
Set<String> solution1 = new HashSet<String>();
Collections.addAll(solution1, v1);
Set<String> solution2 = new HashSet<String>();
Collections.addAll(solution2, v2);
assertEquals(0.0, mincut.minCutWeight(), 0.000001);
assertTrue(mincut.minCut().equals(solution1) ||
mincut.minCut().equals(solution2) );
}
/**
* Test of StoerWagnerMinimumCut on empty and small graphs
*/
public void testMinCutSmall()
{
SimpleGraph<String, DefaultEdge> g =
new SimpleGraph<String, DefaultEdge>(DefaultEdge.class);
StoerWagnerMinimumCut<String, DefaultEdge> mincut;
// 2 vertices, 1 edge
g.addVertex(v1);
g.addVertex(v2);
g.addEdge(v1, v2);
Set<String> solution1 = new HashSet<String>();
Collections.addAll(solution1, v1);
Set<String> solution2 = new HashSet<String>();
Collections.addAll(solution2, v2);
mincut = new StoerWagnerMinimumCut<String, DefaultEdge>(g);
assertEquals(1.0, mincut.minCutWeight(), 0.000001);
assertTrue(mincut.minCut().equals(solution1) ||
mincut.minCut().equals(solution2) );
}
}
// End StoerWagnerMinimumCutTest.java