org.jgrapht.generate.RingGraphGenerator Maven / Gradle / Ivy
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/*
* (C) Copyright 2003-2023, by John V Sichi and Contributors.
*
* JGraphT : a free Java graph-theory library
*
* See the CONTRIBUTORS.md file distributed with this work for additional
* information regarding copyright ownership.
*
* This program and the accompanying materials are made available under the
* terms of the Eclipse Public License 2.0 which is available at
* http://www.eclipse.org/legal/epl-2.0, or the
* GNU Lesser General Public License v2.1 or later
* which is available at
* http://www.gnu.org/licenses/old-licenses/lgpl-2.1-standalone.html.
*
* SPDX-License-Identifier: EPL-2.0 OR LGPL-2.1-or-later
*/
package org.jgrapht.generate;
import org.jgrapht.*;
import java.util.*;
/**
* Generates a ring graph of any size. A ring graph is a graph that contains a single cycle that
* passes through all its vertices exactly once. For a directed graph, the generated edges are
* oriented consistently around the ring.
*
* @param the graph vertex type
* @param the graph edge type
*
* @author John V. Sichi
*/
public class RingGraphGenerator
implements GraphGenerator
{
private final int size;
/**
* Construct a new RingGraphGenerator.
*
* @param size number of vertices to be generated
*
* @throws IllegalArgumentException if the specified size is negative.
*/
public RingGraphGenerator(int size)
{
if (size < 0) {
throw new IllegalArgumentException("must be non-negative");
}
this.size = size;
}
/**
* {@inheritDoc}
*/
@Override
public void generateGraph(Graph target, Map resultMap)
{
if (size < 1) {
return;
}
Map privateMap = new HashMap<>();
new LinearGraphGenerator(size).generateGraph(target, privateMap);
V startVertex = privateMap.get(LinearGraphGenerator.START_VERTEX);
V endVertex = privateMap.get(LinearGraphGenerator.END_VERTEX);
target.addEdge(endVertex, startVertex);
}
}