Package solver.constraints.nary.alldifferent

Source Code of solver.constraints.nary.alldifferent.AllDifferent

/**
*  Copyright (c) 1999-2014, Ecole des Mines de Nantes
*  All rights reserved.
*  Redistribution and use in source and binary forms, with or without
*  modification, are permitted provided that the following conditions are met:
*
*      * Redistributions of source code must retain the above copyright
*        notice, this list of conditions and the following disclaimer.
*      * Redistributions in binary form must reproduce the above copyright
*        notice, this list of conditions and the following disclaimer in the
*        documentation and/or other materials provided with the distribution.
*      * Neither the name of the Ecole des Mines de Nantes nor the
*        names of its contributors may be used to endorse or promote products
*        derived from this software without specific prior written permission.
*
*  THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
*  EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
*  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
*  DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY
*  DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
*  (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
*  LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
*  ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
*  (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
*  SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/

package solver.constraints.nary.alldifferent;

import solver.constraints.Constraint;
import solver.constraints.Propagator;
import solver.constraints.binary.PropNotEqualX_Y;
import solver.constraints.nary.cnf.PropTrue;
import solver.variables.IntVar;

/**
* Ensures that all variables from VARS take a different value.
* The consistency level should be chosen among "AC", "BC", "FC" and "DEFAULT".
*/
public class AllDifferent extends Constraint {

  public static enum Type {
    AC, BC, FC, NEQS, DEFAULT
  }

  public AllDifferent(IntVar[] vars, String type) {
    super("AllDifferent",createPropagators(vars, type));
  }

  private static Propagator<IntVar>[] createPropagators(IntVar[] VARS, String consistency) {
    if(VARS.length<=1){
      return new Propagator[]{new PropTrue(VARS[0].getSolver().ONE)};
    }
    switch (AllDifferent.Type.valueOf(consistency)) {
      case NEQS: {
        int s = VARS.length;
        int k = 0;
        Propagator[] props = new Propagator[(s * s - s) / 2];
        for (int i = 0; i < s - 1; i++) {
          for (int j = i + 1; j < s; j++) {
            props[k++] = new PropNotEqualX_Y(VARS[i], VARS[j]);
          }
        }
        return props;
      }
      case FC: return new Propagator[]{new PropAllDiffInst(VARS)};
      case BC: return new Propagator[]{new PropAllDiffInst(VARS), new PropAllDiffBC(VARS)};
      case AC: return new Propagator[]{new PropAllDiffInst(VARS), new PropAllDiffAC(VARS)};
      case DEFAULT:
      default:
        // adds a Probabilistic AC (only if at least some variables have an enumerated domain)
        boolean enumDom = false;
        for (int i = 0; i < VARS.length && !enumDom; i++) {
          if (VARS[i].hasEnumeratedDomain()) {
            enumDom = true;
          }
        }
        if (enumDom) {
          return new Propagator[]{new PropAllDiffInst(VARS), new PropAllDiffBC(VARS), new PropAllDiffAdaptative(VARS)};
        } else {
          return createPropagators(VARS,"BC");
        }
    }
  }
}
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