Add new flow algorithm Edmonds-Karp.

src-test/org/graphstream/algorithm/flow/test/TestEdmondsKarpAlgorithm.java

+/*
+ * Copyright 2006 - 2012
+ *     Stefan Balev     <stefan.balev@graphstream-project.org>
+ *     Julien Baudry	<julien.baudry@graphstream-project.org>
+ *     Antoine Dutot	<antoine.dutot@graphstream-project.org>
+ *     Yoann Pigné		<yoann.pigne@graphstream-project.org>
+ *     Guilhelm Savin	<guilhelm.savin@graphstream-project.org>
+ * 
+ * This file is part of GraphStream <http://graphstream-project.org>.
+ * 
+ * GraphStream is a library whose purpose is to handle static or dynamic
+ * graph, create them from scratch, file or any source and display them.
+ * 
+ * This program is free software distributed under the terms of two licenses, the
+ * CeCILL-C license that fits European law, and the GNU Lesser General Public
+ * License. You can  use, modify and/ or redistribute the software under the terms
+ * of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
+ * URL <http://www.cecill.info> or under the terms of the GNU LGPL as published by
+ * the Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ * 
+ * This program 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 program.  If not, see <http://www.gnu.org/licenses/>.
+ * 
+ * The fact that you are presently reading this means that you have had
+ * knowledge of the CeCILL-C and LGPL licenses and that you accept their terms.
+ */
+package org.graphstream.algorithm.flow.test;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.graphstream.algorithm.flow.EdmondsKarpAlgorithm;
+import org.graphstream.algorithm.flow.FlowAlgorithm;
+
+public class TestEdmondsKarpAlgorithm extends TestFlowAlgorithm {
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see
+	 * org.graphstream.algorithm.flow.test.TestFlowAlgorithm#getGraphStream()
+	 */
+	public InputStream getGraphStream() throws IOException {
+		return getClass().getResourceAsStream(
+				"data/TestFordFulkersonAlgorithm.dgs");
+	}
+
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see
+	 * org.graphstream.algorithm.flow.test.TestFlowAlgorithm#getFlowAlgorithm()
+	 */
+	public FlowAlgorithm getFlowAlgorithm() {
+		return new EdmondsKarpAlgorithm();
+	}
+}

src-test/org/graphstream/algorithm/flow/test/TestFlowAlgorithm.java

+/*
+ * Copyright 2006 - 2012
+ *     Stefan Balev     <stefan.balev@graphstream-project.org>
+ *     Julien Baudry	<julien.baudry@graphstream-project.org>
+ *     Antoine Dutot	<antoine.dutot@graphstream-project.org>
+ *     Yoann Pigné		<yoann.pigne@graphstream-project.org>
+ *     Guilhelm Savin	<guilhelm.savin@graphstream-project.org>
+ * 
+ * This file is part of GraphStream <http://graphstream-project.org>.
+ * 
+ * GraphStream is a library whose purpose is to handle static or dynamic
+ * graph, create them from scratch, file or any source and display them.
+ * 
+ * This program is free software distributed under the terms of two licenses, the
+ * CeCILL-C license that fits European law, and the GNU Lesser General Public
+ * License. You can  use, modify and/ or redistribute the software under the terms
+ * of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
+ * URL <http://www.cecill.info> or under the terms of the GNU LGPL as published by
+ * the Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ * 
+ * This program 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 program.  If not, see <http://www.gnu.org/licenses/>.
+ * 
+ * The fact that you are presently reading this means that you have had
+ * knowledge of the CeCILL-C and LGPL licenses and that you accept their terms.
+ */
+package org.graphstream.algorithm.flow.test;
+
+import static org.junit.Assert.assertTrue;
+
+import java.io.IOException;
+import java.io.InputStream;
+
+import org.graphstream.algorithm.flow.FlowAlgorithm;
+import org.graphstream.graph.Graph;
+import org.graphstream.graph.implementations.AdjacencyListGraph;
+import org.graphstream.stream.file.FileSourceDGS;
+import org.junit.Before;
+import org.junit.Test;
+
+public abstract class TestFlowAlgorithm {
+	Graph g;
+	FileSourceDGS dgs;
+
+	public abstract InputStream getGraphStream() throws IOException;
+	
+	public abstract FlowAlgorithm getFlowAlgorithm();
+	
+	@Before
+	public void load() throws IOException {
+		dgs = new FileSourceDGS();
+		g = new AdjacencyListGraph("flow-test");
+
+		dgs.addSink(g);
+		dgs.begin(getGraphStream());
+	}
+
+	@Test
+	public void testFlowAlgorithm() throws IOException {
+		FlowAlgorithm flowAlgo = getFlowAlgorithm();
+		double maximumFlow;
+		
+		flowAlgo.setCapacityAttribute("cap");
+
+		while (dgs.nextStep()) {
+			flowAlgo.init(g, "s", "t");
+			flowAlgo.compute();
+
+			maximumFlow = flowAlgo.getMaximumFlow();
+			assertTrue(maximumFlow == g.getNumber("expected maximum flow"));
+		}
+	}
+}

src-test/org/graphstream/algorithm/flow/test/TestFordFulkersonAlgorithm.java

@@ -31,44 +31,31 @@
  */
 package org.graphstream.algorithm.flow.test;
 
-import static org.junit.Assert.assertTrue;
-
 import java.io.IOException;
+import java.io.InputStream;
 
+import org.graphstream.algorithm.flow.FlowAlgorithm;
 import org.graphstream.algorithm.flow.FordFulkersonAlgorithm;
-import org.graphstream.graph.Graph;
-import org.graphstream.graph.implementations.AdjacencyListGraph;
-import org.graphstream.stream.file.FileSourceDGS;
-import org.junit.Before;
-import org.junit.Test;
-
-public class TestFordFulkersonAlgorithm {
-	Graph g;
-	FileSourceDGS dgs;
-
-	@Before
-	public void load() throws IOException {
-		dgs = new FileSourceDGS();
-		g = new AdjacencyListGraph("test");
 
-		dgs.addSink(g);
-		dgs.begin(getClass().getResourceAsStream(
-				"data/TestFordFulkersonAlgorithm.dgs"));
+public class TestFordFulkersonAlgorithm extends TestFlowAlgorithm {
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see
+	 * org.graphstream.algorithm.flow.test.TestFlowAlgorithm#getGraphStream()
+	 */
+	public InputStream getGraphStream() throws IOException {
+		return getClass().getResourceAsStream(
+				"data/TestFordFulkersonAlgorithm.dgs");
 	}
 
-	@Test
-	public void testFordFulkerson() throws IOException {
-		FordFulkersonAlgorithm flowAlgo = new FordFulkersonAlgorithm();
-		double maximumFlow;
-		
-		flowAlgo.setCapacityAttribute("cap");
-
-		while (dgs.nextStep()) {
-			flowAlgo.init(g, "s", "t");
-			flowAlgo.compute();
-
-			maximumFlow = flowAlgo.getMaximumFlow();
-			assertTrue(maximumFlow == g.getNumber("expected maximum flow"));
-		}
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see
+	 * org.graphstream.algorithm.flow.test.TestFlowAlgorithm#getFlowAlgorithm()
+	 */
+	public FlowAlgorithm getFlowAlgorithm() {
+		return new FordFulkersonAlgorithm();
 	}
 }

src/org/graphstream/algorithm/flow/EdmondsKarpAlgorithm.java

+/*
+ * Copyright 2006 - 2012
+ *     Stefan Balev     <stefan.balev@graphstream-project.org>
+ *     Julien Baudry	<julien.baudry@graphstream-project.org>
+ *     Antoine Dutot	<antoine.dutot@graphstream-project.org>
+ *     Yoann Pigné		<yoann.pigne@graphstream-project.org>
+ *     Guilhelm Savin	<guilhelm.savin@graphstream-project.org>
+ * 
+ * This file is part of GraphStream <http://graphstream-project.org>.
+ * 
+ * GraphStream is a library whose purpose is to handle static or dynamic
+ * graph, create them from scratch, file or any source and display them.
+ * 
+ * This program is free software distributed under the terms of two licenses, the
+ * CeCILL-C license that fits European law, and the GNU Lesser General Public
+ * License. You can  use, modify and/ or redistribute the software under the terms
+ * of the CeCILL-C license as circulated by CEA, CNRS and INRIA at the following
+ * URL <http://www.cecill.info> or under the terms of the GNU LGPL as published by
+ * the Free Software Foundation, either version 3 of the License, or (at your
+ * option) any later version.
+ * 
+ * This program 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 program.  If not, see <http://www.gnu.org/licenses/>.
+ * 
+ * The fact that you are presently reading this means that you have had
+ * knowledge of the CeCILL-C and LGPL licenses and that you accept their terms.
+ */
+package org.graphstream.algorithm.flow;
+
+import java.util.Arrays;
+import java.util.LinkedList;
+
+import org.graphstream.graph.Edge;
+import org.graphstream.graph.Node;
+
+public class EdmondsKarpAlgorithm extends FordFulkersonAlgorithm {
+	/*
+	 * (non-Javadoc)
+	 * 
+	 * @see
+	 * org.graphstream.algorithm.flow.FordFulkersonAlgorithm#findPath(java.util
+	 * .LinkedList, org.graphstream.graph.Node, org.graphstream.graph.Node)
+	 */
+	protected double findPath(LinkedList<Node> path, Node source, Node target) {
+		LinkedList<Node> Q = new LinkedList<Node>();
+		Node u;
+		int[] P = new int[source.getGraph().getNodeCount()];
+		double[] M = new double[source.getGraph().getNodeCount()];
+		double r;
+
+		Arrays.fill(P, -1);
+		P[source.getIndex()] = -2;
+		M[source.getIndex()] = Double.MAX_VALUE;
+
+		Q.add(source);
+
+		while (Q.size() > 0) {
+			u = Q.pop();
+
+			for (int i = 0; i < u.getDegree(); i++) {
+				Edge e = u.getEdge(i);
+				Node v = e.getOpposite(u);
+
+				r = getCapacity(u, v) - getFlow(u, v);
+
+				if (r > 0 && P[v.getIndex()] == -1) {
+					P[v.getIndex()] = u.getIndex();
+					M[v.getIndex()] = Math.min(M[u.getIndex()], r);
+
+					if (v != target)
+						Q.push(v);
+					else {
+						u = target;
+
+						do {
+							path.addFirst(u);
+							u = flowGraph.getNode(P[u.getIndex()]);
+						} while (u != source);
+
+						path.addFirst(u);
+						return M[target.getIndex()];
+					}
+				}
+			}
+		}
+
+		return 0;
+	}
+}

src/org/graphstream/algorithm/flow/FordFulkersonAlgorithm.java

@@ -72,19 +72,10 @@ public class FordFulkersonAlgorithm extends FlowAlgorithmBase {
 			setFlow(e.getNode1(), e.getNode0(), 0);
 		}
 
+		double minCf;
 		LinkedList<Node> path = new LinkedList<Node>();
-		path.add(source);
-
-		while (findPath(path, source, sink)) {
-			double minCf = Double.MAX_VALUE;
-
-			for (int i = 1; i < path.size(); i++) {
-				Node u = path.get(i - 1);
-				Node v = path.get(i);
-
-				minCf = Math.min(minCf, getCapacity(u, v) - getFlow(u, v));
-			}
 
+		while ((minCf = findPath(path, source, sink)) > 0) {
 			for (int i = 1; i < path.size(); i++) {
 				Node u = path.get(i - 1);
 				Node v = path.get(i);
@@ -94,7 +85,6 @@ public class FordFulkersonAlgorithm extends FlowAlgorithmBase {
 			}
 
 			path.clear();
-			path.add(source);
 		}
 
 		double flow = 0;
@@ -105,9 +95,13 @@ public class FordFulkersonAlgorithm extends FlowAlgorithmBase {
 		maximumFlow = flow;
 	}
 
-	protected boolean findPath(LinkedList<Node> path, Node source, Node target) {
+	protected double findPath(LinkedList<Node> path, Node source, Node target) {
+		path.addLast(source);
+		
 		if (source == target)
-			return true;
+			return Double.MAX_VALUE;
+
+		double minCf;
 
 		for (int i = 0; i < source.getDegree(); i++) {
 			Edge e = source.getEdge(i);
@@ -115,15 +109,13 @@ public class FordFulkersonAlgorithm extends FlowAlgorithmBase {
 
 			if (getCapacity(source, o) - getFlow(source, o) > 0
 					&& !path.contains(o)) {
-				path.addLast(o);
-
-				if (findPath(path, o, target))
-					return true;
-
-				path.removeLast();
+				if ((minCf = findPath(path, o, target)) > 0)
+					return Math.min(minCf,
+							getCapacity(source, o) - getFlow(source, o));
 			}
 		}
-
-		return false;
+		
+		path.removeLast();
+		return 0;
 	}
 }