com.salesforce.jgrapht.generate.HyperCubeGraphGenerator Maven / Gradle / Ivy

Go to download

Show more of this group Show more artifacts with this name
Show all versions of AptSpringProcessor Show documentation

This project contains the apt processor that implements all the checks enumerated in @Verify. It is a self contained, and shaded jar.

The newest version!

/*
 * (C) Copyright 2008-2018, by Andrew Newell 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 com.salesforce.jgrapht.generate;

import com.salesforce.jgrapht.*;

import java.util.*;

/**
 * Generates a hyper cube graph of
 * any size. This is a graph that can be represented by bit strings, so for an n-dimensional
 * hypercube each vertex resembles an n-length bit string. Then, two vertices are adjacent if and
 * only if their bitstring differ by exactly one element.
 * 
 * @param  the graph vertex type
 * @param  the graph edge type
 *
 * @author Andrew Newell
 */
public class HyperCubeGraphGenerator
    implements
    GraphGenerator
{
    private int dim;

    /**
     * Creates a new generator
     *
     * @param dim the dimension of the hypercube
     */
    public HyperCubeGraphGenerator(int dim)
    {
        this.dim = dim;
    }

    @Override
    public void generateGraph(Graph target, Map resultMap)
    {
        // Vertices are created, and they are included in the resultmap as their
        // bitstring representation
        int order = (int) Math.pow(2, dim);
        LinkedList vertices = new LinkedList<>();
        for (int i = 0; i < order; i++) {
            V newVertex = target.addVertex();

            vertices.add(newVertex);
            if (resultMap != null) {
                StringBuilder s = new StringBuilder(Integer.toBinaryString(i));
                while (s.length() < dim) {
                    s.insert(0, "0");
                }
                resultMap.put(s.toString(), newVertex);
            }
        }

        // Two vertices will have an edge if their bitstrings differ by exactly
        // 1 element
        for (int i = 0; i < order; i++) {
            for (int j = i + 1; j < order; j++) {
                for (int z = 0; z < dim; z++) {
                    if ((j ^ i) == (1 << z)) {
                        target.addEdge(vertices.get(i), vertices.get(j));
                        break;
                    }
                }
            }
        }
    }
}