contiguity_transition.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 System.Collections;
using System.Linq;
using System.Diagnostics;
using Google.OrTools.ConstraintSolver;

public class ContiguityRegular
{

  static void MyContiguity(Solver solver, IntVar[] x) {

    // the DFA (for regular)
    int initial_state = 1;

    // all states are accepting states
    int[] accepting_states = {1,2,3};

    // The regular expression 0*1*0* {state, input, next state}
    long[][] transition_tuples = {
      new long[] {1, 0, 1},
      new long[] {1, 1, 2},
      new long[] {2, 0, 3},
      new long[] {2, 1, 2},
      new long[] {3, 0, 3}
    };

    IntTupleSet result = new IntTupleSet(3);
    result.InsertAll(transition_tuples);

    solver.Add(x.Transition(result,
                            initial_state,
                            accepting_states));
  }


  /**
   *
   * Global constraint contiguity using Transition
   *
   * This version use the built-in TransitionConstraint.
   *
   * From Global Constraint Catalogue
   * http://www.emn.fr/x-info/sdemasse/gccat/Cglobal_contiguity.html
   * """
   * Enforce all variables of the VARIABLES collection to be assigned to 0 or 1.
   * In addition, all variables assigned to value 1 appear contiguously.
   *
   * Example:
   * (<0, 1, 1, 0>)
   *
   * The global_contiguity constraint holds since the sequence 0 1 1 0 contains
   * no more than one group of contiguous 1.
   * """
   *
   * Also see http://www.hakank.org/or-tools/contiguity_regular.py
   *
   */
  private static void Solve()
  {
    Solver solver = new Solver("ContiguityRegular");

    //
    // Data
    //
    int n = 7; // length of the array


    //
    // Decision variables
    //

    IntVar[] reg_input = solver.MakeIntVarArray(n, 0, 1, "reg_input");


    //
    // Constraints
    //
    MyContiguity(solver, reg_input);


    //
    // Search
    //
    DecisionBuilder db = solver.MakePhase(reg_input,
                                          Solver.CHOOSE_FIRST_UNBOUND,
                                          Solver.ASSIGN_MIN_VALUE);

    solver.NewSearch(db);

    while (solver.NextSolution()) {
      for(int i = 0; i < n; i++) {
        Console.Write((reg_input[i].Value()) + " ");
      }
      Console.WriteLine();
    }

    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();
  }
}