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*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
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package solver.search.strategy.selectors.variables;
import gnu.trove.list.array.TIntArrayList;
import solver.search.strategy.selectors.VariableEvaluator;
import solver.search.strategy.selectors.VariableSelector;
import solver.variables.Variable;
/**
* <b>Random</b> variable selector.
* It chooses variables randomly, among uninstantiated ones.
* <br/>
*
* @author Charles Prud'homme
* @since 2 juil. 2010
*/
public class Random<T extends Variable> implements VariableSelector<T>, VariableEvaluator<T> {
TIntArrayList sets;
java.util.Random random;
public Random(long seed) {
sets = new TIntArrayList();
random = new java.util.Random(seed);
}
@Override
public T getVariable(T[] variables) {
sets.clear();
for (int idx = 0; idx < variables.length; idx++) {
if (!variables[idx].isInstantiated()) {
sets.add(idx);
}
}
if (sets.size() > 0) {
int rand_idx = sets.get(random.nextInt(sets.size()));
return variables[rand_idx];
} else return null;
}
@Override
public double evaluate(T variable) {
return random.nextDouble();
}
}