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/* WienerIndex.java
* =========================================================================
* This file is part of the GrInvIn project - http://www.grinvin.org
*
* Copyright (C) 2005-2008 Universiteit Gent
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 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
* General Public License for more details.
*
* A copy of the GNU General Public License can be found in the file
* LICENSE.txt provided with the source distribution of this program (see
* the META-INF directory in the source jar). This license can also be
* found on the GNU website at http://www.gnu.org/licenses/gpl.html.
*
* If you did not receive a copy of the GNU General Public License along
* with this program, contact the lead developer, or write to the Free
* Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA.
*/
package org.grinvin.invariants.computers.chemical;
import org.grinvin.graphs.GraphBundleView;
import org.grinvin.invariants.computers.AbstractInvariantComputer;
import org.grinvin.invariants.values.IntegerValue;
/**
* computes the Wiener index of the graph (sum of all the distances in the graph).
*/
public class WienerIndex extends AbstractInvariantComputer {
public IntegerValue compute(GraphBundleView bundle) {
int[][] distanceMatrix = bundle.distanceMatrix();
int n = distanceMatrix.length;
if (n <= 1) {
if (n == 0)
return IntegerValue.undefinedValue(this);
else
return new IntegerValue(0, this);
}
int wienerIndex=0;
for(int i=0; i < n-1; i++)
for (int j=i+1; j<n; j++){
if(distanceMatrix[i][j]==0){
//vertices in different components of the graph
return IntegerValue.positiveInfinity(this);
}
wienerIndex+=distanceMatrix[i][j];
}
return new IntegerValue(wienerIndex, this);
}
public String getInvariantId() {
return "org.grinvin.invariants.WienerIndex";
}
}
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