least_diff.cs

//
// Copyright 2012 Hakan Kjellerstrand
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

using System;
using Google.OrTools.ConstraintSolver;

public class LeastDiff
{
  /**
   *
   * Solve the Least diff problem
   * For more info, see http://www.hakank.org/google_or_tools/least_diff.py
   *
   */
  private static void Solve()
  {
    Solver solver = new Solver("LeastDiff");

    //
    // Decision variables
    //
    IntVar A = solver.MakeIntVar(0, 9, "A");
    IntVar B = solver.MakeIntVar(0, 9, "B");
    IntVar C = solver.MakeIntVar(0, 9, "C");
    IntVar D = solver.MakeIntVar(0, 9, "D");
    IntVar E = solver.MakeIntVar(0, 9, "E");
    IntVar F = solver.MakeIntVar(0, 9, "F");
    IntVar G = solver.MakeIntVar(0, 9, "G");
    IntVar H = solver.MakeIntVar(0, 9, "H");
    IntVar I = solver.MakeIntVar(0, 9, "I");
    IntVar J = solver.MakeIntVar(0, 9, "J");

    IntVar[] all = new IntVar[] {A,B,C,D,E,F,G,H,I,J};
    int[] coeffs = {10000,1000,100,10,1};
    IntVar x = new IntVar[]{A,B,C,D,E}.ScalProd(coeffs).Var();
    IntVar y = new IntVar[]{F,G,H,I,J}.ScalProd(coeffs).Var();
    IntVar diff = (x - y).VarWithName("diff");


    //
    // Constraints
    //
    solver.Add(all.AllDifferent());
    solver.Add(A > 0);
    solver.Add(F > 0);
    solver.Add(diff > 0);


    //
    // Objective
    //
    OptimizeVar obj = diff.Minimize(1);

    //
    // Search
    //
    DecisionBuilder db = solver.MakePhase(all,
                                          Solver.CHOOSE_PATH,
                                          Solver.ASSIGN_MIN_VALUE);

    solver.NewSearch(db, obj);
    while (solver.NextSolution()) {
      Console.WriteLine("{0} - {1} = {2}  ({3}",x.Value(), y.Value(), diff.Value(), diff.ToString());
    }

    Console.WriteLine("\nSolutions: {0}", solver.Solutions());
    Console.WriteLine("WallTime: {0}ms", solver.WallTime());
    Console.WriteLine("Failures: {0}", solver.Failures());
    Console.WriteLine("Branches: {0} ", solver.Branches());

    solver.EndSearch();

  }

  public static void Main(String[] args)
  {
    Solve();
  }
}