/**
*
*/
package vroom.trsp.datamodel;
import umontreal.iro.lecuyer.rng.RandomStream;
/**
* <code>NodeSetSolutionHasher</code> is an implementation for {@link TRSPSolution} of the hashing procedure based on
* the one proposed in:
* <p>
* Groër, C.; Golden, B. & Wasil, E. <br/>
* A library of local search heuristics for the vehicle routing problem <br/>
* Mathematical Programming Computation, Springer Berlin / Heidelberg, 2010, 2, 79-101
* </p>
* <p>
* The main difference with {@link GroerSolutionHasher} is that the sequence of nodes is not considered when evaluating
* a tour, but only the subset of requests that are visited, and the associated technician. Consequently, two tours
* visiting the same set of requests in a different order will have the same hash. This is in particular useful when
* maintaining a pool of tours for a set covering formulation.
* </p>
* <p>
* Creation date: May 23, 2011 - 10:52:45 AM
*
* @author Victor Pillac, <a href="http://uniandes.edu.co">Universidad de Los Andes</a>-<a
* href="http://copa.uniandes.edu.co">Copa</a> <a href="http://www.emn.fr">Ecole des Mines de Nantes</a>-<a
* href="http://www.irccyn.ec-nantes.fr/irccyn/d/en/equipes/Slp">SLP</a>
* @version 1.0
*/
public class NodeSetSolutionHasher extends GroerSolutionHasher {
public NodeSetSolutionHasher(TRSPInstance instance, RandomStream rndStream) {
super(instance, rndStream);
}
/**
* Hashing of a tour from a start value
*
* @param tour
* the tour to be hashed
* @param hash
* the initial hash value
* @return the hash of the tour depending on the initial hash value
*/
@Override
int hashTour(ITRSPTour tour, int hash) {
for (int r : tour) {
// if (tour.isVisited(r)) {
hash ^= mRndInts[r % mRndInts.length];
// }
}
return hash;
}
}