strimko2.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.IO;
using System.Linq;
using System.Text.RegularExpressions;
using Google.OrTools.ConstraintSolver;

public class Strimko2
{

  /**
   *
   * Solves a Strimko problem.
   * See http://www.hakank.org/google_or_tools/strimko2.py
   *
   */
  private static void Solve()
  {

    Solver solver = new Solver("Strimko2");

    //
    // data
    //
    int[,] streams = {{1,1,2,2,2,2,2},
                      {1,1,2,3,3,3,2},
                      {1,4,1,3,3,5,5},
                      {4,4,3,1,3,5,5},
                      {4,6,6,6,7,7,5},
                      {6,4,6,4,5,5,7},
                      {6,6,4,7,7,7,7}};

    // Note: This is 1-based
    int[,] placed = {{2,1,1},
                     {2,3,7},
                     {2,5,6},
                     {2,7,4},
                     {3,2,7},
                     {3,6,1},
                     {4,1,4},
                     {4,7,5},
                     {5,2,2},
                     {5,6,6}};

    int n = streams.GetLength(0);
    int num_placed = placed.GetLength(0);

    //
    // Decision variables
    //
    IntVar[,] x = solver.MakeIntVarMatrix(n, n, 1, n, "x");
    IntVar[] x_flat = x.Flatten();

    //
    // Constraints
    //
    // all rows and columns must be unique, i.e. a Latin Square
    for(int i = 0; i < n; i++) {
      IntVar[] row = new IntVar[n];
      IntVar[] col = new IntVar[n];
      for(int j = 0; j < n; j++) {
        row[j] = x[i,j];
        col[j] = x[j,i];
      }

      solver.Add(row.AllDifferent());
      solver.Add(col.AllDifferent());
    }

    // streams
    for(int s = 1; s <= n; s++) {
      IntVar[] tmp = (from i in Enumerable.Range(0, n)
                      from j in Enumerable.Range(0, n)
                      where streams[i,j] == s
                      select x[i,j]).ToArray();
      solver.Add(tmp.AllDifferent());

    }

    // placed
    for(int i = 0; i <  num_placed; i++) {
      // note: also adjust to 0-based
      solver.Add(x[placed[i,0] - 1,placed[i,1] - 1] ==  placed[i,2]);
    }

    //
    // Search
    //
    DecisionBuilder db = solver.MakePhase(x_flat,
                                          Solver.INT_VAR_DEFAULT,
                                          Solver.INT_VALUE_DEFAULT);

    solver.NewSearch(db);

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