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Open-source constraint solver.
There is a newer version: 4.10.16
/**
 * Copyright (c) 2016, 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:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. 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.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *    This product includes software developed by the .
 * 4. Neither the name of the  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  ''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  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 org.chocosolver.solver.constraints.ternary;

import org.chocosolver.solver.Model;
import org.chocosolver.solver.constraints.Constraint;
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.solver.variables.impl.IntervalIntVarImpl;

import static java.lang.Math.max;

/**
 * X = MAX(Y,Z)
 * 

 *
 * @author Charles Prud'homme
 * @since 19/04/11
 */
public class Max extends Constraint {

    public Max(IntVar X, IntVar Y, IntVar Z) {
        super("Max",new PropMaxBC(X, Y, Z));
    }

    public static IntVar var(IntVar a, IntVar b) {
        if (a.getLB() >= b.getUB()) {
            return a;
        } else if (b.getLB() >= a.getUB()) {
            return b;
        } else {
            Model model = a.getModel();
            IntVar z = new IntervalIntVarImpl(model.generateName("MAX_"),
                    max(a.getLB(), b.getLB()), max(a.getUB(), b.getUB()), model);
            model.max(z, a, b).post();
            return z;
        }
    }
}