Add a solver with the "Divide by 2" feature. Correctthe previous version

and remove it from the standard process.

org.sat4j.pb/src/main/java/org/sat4j/pb/SolverFactory.java

@@ -68,6 +68,7 @@ import org.sat4j.pb.core.PBSolverCP;
 import org.sat4j.pb.core.PBSolverCPCardLearning;
 import org.sat4j.pb.core.PBSolverCPClauseLearning;
 import org.sat4j.pb.core.PBSolverCPLong;
+import org.sat4j.pb.core.PBSolverCPLongDivideBy2;
 import org.sat4j.pb.core.PBSolverCPLongReduceToCard;
 import org.sat4j.pb.core.PBSolverCPLongRounding;
 //import org.sat4j.pb.core.PBSolverCard;
@@ -632,6 +633,18 @@ public final class SolverFactory extends ASolverFactory<IPBSolver> {
         return solver;
     }
 
+    private static PBSolverCP newPBCPStarDivideBy2(PBDataStructureFactory dsf,
+            IOrder order, boolean noRemove) {
+        MiniSATLearning<PBDataStructureFactory> learning = new MiniSATLearning<PBDataStructureFactory>();
+        PBSolverCP solver = new PBSolverCPLongDivideBy2(learning, dsf, order,
+                noRemove);
+        learning.setDataStructureFactory(solver.getDSFactory());
+        learning.setVarActivityListener(solver);
+        solver.setRestartStrategy(new ArminRestarts());
+        solver.setLearnedConstraintsDeletionStrategy(solver.lbd_based);
+        return solver;
+    }
+
     private static PBSolverCP newPBCPStarRounding(PBDataStructureFactory dsf,
             IOrder order, boolean noRemove) {
         MiniSATLearning<PBDataStructureFactory> learning = new MiniSATLearning<PBDataStructureFactory>();
@@ -704,6 +717,11 @@ public final class SolverFactory extends ASolverFactory<IPBSolver> {
                 new VarOrderHeapObjective(), true);
     }
 
+    public static IPBSolver newCuttingPlanesStarDivideBy2() {
+        return newPBCPStarDivideBy2(new PBMaxClauseCardConstrDataStructure(),
+                new VarOrderHeapObjective(), true);
+    }
+
     /**
      * Cutting Planes based solver. The inference during conflict analysis is
      * based on cutting planes instead of resolution as in a SAT solver.

org.sat4j.pb/src/main/java/org/sat4j/pb/constraints/pb/MapPb.java

@@ -75,10 +75,14 @@ public class MapPb implements IDataStructurePB {
     }
 
     public int reduceCoeffsByPower2() {
-        int nbBits = 1;
-        for (int i = 0; i < this.weightedLits.size() && nbBits > 0; i++)
+        assert this.weightedLits.size() > 0;
+        int nbBits = this.weightedLits.getCoef(0).bitLength();
+        for (int i = 0; i < this.weightedLits.size() && nbBits > 0; i++) {
             nbBits = Math.min(nbBits,
                     this.weightedLits.getCoef(i).getLowestSetBit());
+            if (nbBits == 0)
+                break;
+        }
         if (nbBits > 0) {
             for (int i = 0; i < this.weightedLits.size(); i++) {
                 this.weightedLits.changeCoef(i,

org.sat4j.pb/src/main/java/org/sat4j/pb/core/PBSolverCP.java

@@ -164,12 +164,6 @@ public class PBSolverCP extends PBSolver {
         }
 
         // assertive PB-constraint is build and referenced
-        int nbBits = confl.reduceCoeffsByPower2();
-        if (nbBits > 0) {
-            stats.numberOfReductionsByPower2++;
-            stats.numberOfRightShiftsForCoeffs = stats.numberOfRightShiftsForCoeffs
-                    + nbBits;
-        }
         confl.postProcess(currentLevel);
         PBConstr resConstr = (PBConstr) this.dsfactory
                 .createUnregisteredPseudoBooleanConstraint(confl);

org.sat4j.pb/src/main/java/org/sat4j/pb/core/PBSolverCPLongDivideBy2.java

+package org.sat4j.pb.core;
+
+import org.sat4j.minisat.core.IOrder;
+import org.sat4j.minisat.core.LearningStrategy;
+import org.sat4j.minisat.core.RestartStrategy;
+import org.sat4j.minisat.core.SearchParams;
+import org.sat4j.pb.constraints.pb.ConflictMap;
+import org.sat4j.pb.constraints.pb.ConflictMapReduceToClause;
+import org.sat4j.pb.constraints.pb.IConflict;
+import org.sat4j.pb.constraints.pb.PBConstr;
+
+public class PBSolverCPLongDivideBy2 extends PBSolverCPLong {
+
+    public PBSolverCPLongDivideBy2(
+            LearningStrategy<PBDataStructureFactory> learner,
+            PBDataStructureFactory dsf, IOrder order) {
+        super(learner, dsf, order);
+        // TODO Auto-generated constructor stub
+    }
+
+    public PBSolverCPLongDivideBy2(
+            LearningStrategy<PBDataStructureFactory> learner,
+            PBDataStructureFactory dsf, SearchParams params, IOrder order,
+            RestartStrategy restarter) {
+        super(learner, dsf, params, order, restarter);
+        // TODO Auto-generated constructor stub
+    }
+
+    public PBSolverCPLongDivideBy2(
+            LearningStrategy<PBDataStructureFactory> learner,
+            PBDataStructureFactory dsf, SearchParams params, IOrder order) {
+        super(learner, dsf, params, order);
+        // TODO Auto-generated constructor stub
+    }
+
+    public PBSolverCPLongDivideBy2(
+            LearningStrategy<PBDataStructureFactory> learner,
+            PBDataStructureFactory dsf, IOrder order, boolean noRemove) {
+        super(learner, dsf, order, noRemove);
+        // TODO Auto-generated constructor stub
+    }
+
+    public PBSolverCPLongDivideBy2(
+            LearningStrategy<PBDataStructureFactory> learner,
+            PBDataStructureFactory dsf, SearchParams params, IOrder order,
+            RestartStrategy restarter, boolean noRemove) {
+        super(learner, dsf, params, order, restarter, noRemove);
+        // TODO Auto-generated constructor stub
+    }
+
+    public PBSolverCPLongDivideBy2(
+            LearningStrategy<PBDataStructureFactory> learner,
+            PBDataStructureFactory dsf, SearchParams params, IOrder order,
+            boolean noRemove) {
+        super(learner, dsf, params, order, noRemove);
+        // TODO Auto-generated constructor stub
+    }
+
+    @Override
+    protected IConflict chooseConflict(PBConstr myconfl, int level) {
+        return ConflictMapReduceToClause.createConflict(myconfl, level,
+                noRemove, ConflictMap.POSTPROCESSDIVIDEBY2, stats);
+    }
+
+    @Override
+    public String toString(String prefix) {
+        return super.toString(prefix) + "\n" + prefix
+                + "Performs a post-processing after conflict analysis in order to divide by 2 as much as possible coefficients of learned constraints";
+    }
+
+}

org.sat4j.pb/src/test/java/org/sat4j/pb/constraints/PBCPMaxClauseCardConstrLearningDivideBy2Test.java

+package org.sat4j.pb.constraints;
+
+import org.sat4j.pb.IPBSolver;
+import org.sat4j.pb.SolverFactory;
+
+public class PBCPMaxClauseCardConstrLearningDivideBy2Test
+        extends AbstractPseudoBooleanAndPigeonHoleTest {
+
+    public PBCPMaxClauseCardConstrLearningDivideBy2Test(String arg) {
+        super(arg);
+        // TODO Auto-generated constructor stub
+    }
+
+    @Override
+    protected IPBSolver createSolver() {
+        return SolverFactory.newCuttingPlanesStarDivideBy2();
+    }
+
+}