TspCircuitBoard.cs

// Copyright 2010-2018 Google LLC
// 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.

// [START program]
// [START import]
using System;
using System.Collections.Generic;
using Google.OrTools.ConstraintSolver;
// [END import]

/// <summary>
///   Minimal TSP.
///   A description of the problem can be found here:
///   http://en.wikipedia.org/wiki/Travelling_salesman_problem.
/// </summary>
public class TspCircuitBoard {
  // [START data_model]
  class DataModel {
    public int[,] Locations = {
      {288, 149}, {288, 129}, {270, 133}, {256, 141}, {256, 157}, {246, 157},
      {236, 169}, {228, 169}, {228, 161}, {220, 169}, {212, 169}, {204, 169},
      {196, 169}, {188, 169}, {196, 161}, {188, 145}, {172, 145}, {164, 145},
      {156, 145}, {148, 145}, {140, 145}, {148, 169}, {164, 169}, {172, 169},
      {156, 169}, {140, 169}, {132, 169}, {124, 169}, {116, 161}, {104, 153},
      {104, 161}, {104, 169}, {90, 165}, {80, 157}, {64, 157}, {64, 165},
      {56, 169}, {56, 161}, {56, 153}, {56, 145}, {56, 137}, {56, 129},
      {56, 121}, {40, 121}, {40, 129}, {40, 137}, {40, 145}, {40, 153},
      {40, 161}, {40, 169}, {32, 169}, {32, 161}, {32, 153}, {32, 145},
      {32, 137}, {32, 129}, {32, 121}, {32, 113}, {40, 113}, {56, 113},
      {56, 105}, {48, 99}, {40, 99}, {32, 97}, {32, 89}, {24, 89}, {16, 97},
      {16, 109}, {8, 109}, {8, 97}, {8, 89}, {8, 81}, {8, 73}, {8, 65},
      {8, 57}, {16, 57}, {8, 49}, {8, 41}, {24, 45}, {32, 41}, {32, 49},
      {32, 57}, {32, 65}, {32, 73}, {32, 81}, {40, 83}, {40, 73}, {40, 63},
      {40, 51}, {44, 43}, {44, 35}, {44, 27}, {32, 25}, {24, 25}, {16, 25},
      {16, 17}, {24, 17}, {32, 17}, {44, 11}, {56, 9}, {56, 17}, {56, 25},
      {56, 33}, {56, 41}, {64, 41}, {72, 41}, {72, 49}, {56, 49}, {48, 51},
      {56, 57}, {56, 65}, {48, 63}, {48, 73}, {56, 73}, {56, 81}, {48, 83},
      {56, 89}, {56, 97}, {104, 97}, {104, 105}, {104, 113}, {104, 121},
      {104, 129}, {104, 137}, {104, 145}, {116, 145}, {124, 145}, {132, 145},
      {132, 137}, {140, 137}, {148, 137}, {156, 137}, {164, 137}, {172, 125},
      {172, 117}, {172, 109}, {172, 101}, {172, 93}, {172, 85}, {180, 85},
      {180, 77}, {180, 69}, {180, 61}, {180, 53}, {172, 53}, {172, 61},
      {172, 69}, {172, 77}, {164, 81}, {148, 85}, {124, 85}, {124, 93},
      {124, 109}, {124, 125}, {124, 117}, {124, 101}, {104, 89}, {104, 81},
      {104, 73}, {104, 65}, {104, 49}, {104, 41}, {104, 33}, {104, 25},
      {104, 17}, {92, 9}, {80, 9}, {72, 9}, {64, 21}, {72, 25}, {80, 25},
      {80, 25}, {80, 41}, {88, 49}, {104, 57}, {124, 69}, {124, 77}, {132, 81},
      {140, 65}, {132, 61}, {124, 61}, {124, 53}, {124, 45}, {124, 37},
      {124, 29}, {132, 21}, {124, 21}, {120, 9}, {128, 9}, {136, 9}, {148, 9},
      {162, 9}, {156, 25}, {172, 21}, {180, 21}, {180, 29}, {172, 29},
      {172, 37}, {172, 45}, {180, 45}, {180, 37}, {188, 41}, {196, 49},
      {204, 57}, {212, 65}, {220, 73}, {228, 69}, {228, 77}, {236, 77},
      {236, 69}, {236, 61}, {228, 61}, {228, 53}, {236, 53}, {236, 45},
      {228, 45}, {228, 37}, {236, 37}, {236, 29}, {228, 29}, {228, 21},
      {236, 21}, {252, 21}, {260, 29}, {260, 37}, {260, 45}, {260, 53},
      {260, 61}, {260, 69}, {260, 77}, {276, 77}, {276, 69}, {276, 61},
      {276, 53}, {284, 53}, {284, 61}, {284, 69}, {284, 77}, {284, 85},
      {284, 93}, {284, 101}, {288, 109}, {280, 109}, {276, 101}, {276, 93},
      {276, 85}, {268, 97}, {260, 109}, {252, 101}, {260, 93}, {260, 85},
      {236, 85}, {228, 85}, {228, 93}, {236, 93}, {236, 101}, {228, 101},
      {228, 109}, {228, 117}, {228, 125}, {220, 125}, {212, 117}, {204, 109},
      {196, 101}, {188, 93}, {180, 93}, {180, 101}, {180, 109}, {180, 117},
      {180, 125}, {196, 145}, {204, 145}, {212, 145}, {220, 145}, {228, 145},
      {236, 145}, {246, 141}, {252, 125}, {260, 129}, {280, 133},
    };
    public int VehicleNumber = 1;
    public int Depot = 0;
  };
  // [END data_model]

  // [START euclidean_distance]
  /// <summary>
  ///   Euclidean distance implemented as a callback. It uses an array of
  ///   positions and computes the Euclidean distance between the two
  ///   positions of two different indices.
  /// </summary>
  static long[,] ComputeEuclideanDistanceMatrix(in int[,] locations) {
    // Calculate the distance matrix using Euclidean distance.
    int locationNumber = locations.GetLength(0);
    long[,] distanceMatrix = new long[locationNumber, locationNumber];
    for (int fromNode = 0; fromNode < locationNumber; fromNode++) {
      for (int toNode = 0; toNode < locationNumber; toNode++) {
        if (fromNode == toNode)
          distanceMatrix[fromNode, toNode] = 0;
        else
          distanceMatrix[fromNode, toNode] = (long)
            Math.Sqrt(
              Math.Pow(locations[toNode, 0] - locations[fromNode, 0], 2) +
              Math.Pow(locations[toNode, 1] - locations[fromNode, 1], 2));
      }
    }
    return distanceMatrix;
  }
  // [END euclidean_distance]

  // [START solution_printer]
  /// <summary>
  ///   Print the solution.
  /// </summary>
  static void PrintSolution(
      in RoutingModel routing,
      in RoutingIndexManager manager,
      in Assignment solution) {
    Console.WriteLine("Objective: {0}", solution.ObjectiveValue());
    // Inspect solution.
    Console.WriteLine("Route:");
    long routeDistance = 0;
    var index = routing.Start(0);
    while (routing.IsEnd(index) == false) {
      Console.Write("{0} -> ", manager.IndexToNode((int)index));
      var previousIndex = index;
      index = solution.Value(routing.NextVar(index));
      routeDistance += routing.GetArcCostForVehicle(previousIndex, index, 0);
    }
    Console.WriteLine("{0}", manager.IndexToNode((int)index));
    Console.WriteLine("Route distance: {0}m", routeDistance);
  }
  // [END solution_printer]

  public static void Main(String[] args) {
    // Instantiate the data problem.
    // [START data]
    DataModel data = new DataModel();
    // [END data]

    // Create Routing Index Manager
    // [START index_manager]
    RoutingIndexManager manager = new RoutingIndexManager(
        data.Locations.GetLength(0),
        data.VehicleNumber,
        data.Depot);
    // [END index_manager]

    // Create Routing Model.
    // [START routing_model]
    RoutingModel routing = new RoutingModel(manager);
    // [END routing_model]

    // Define cost of each arc.
    // [START transit_callback]
    long[,] distanceMatrix = ComputeEuclideanDistanceMatrix(data.Locations);
    int transitCallbackIndex = routing.RegisterTransitCallback(
      (long fromIndex, long toIndex) => {
        // Convert from routing variable Index to distance matrix NodeIndex.
        var fromNode = manager.IndexToNode(fromIndex);
        var toNode = manager.IndexToNode(toIndex);
        return distanceMatrix[fromNode, toNode]; }
    );
    // [END transit_callback]

    // [START arc_cost]
    routing.SetArcCostEvaluatorOfAllVehicles(transitCallbackIndex);
    // [END arc_cost]

    // Setting first solution heuristic.
    // [START parameters]
    RoutingSearchParameters searchParameters =
      operations_research_constraint_solver.DefaultRoutingSearchParameters();
    searchParameters.FirstSolutionStrategy =
      FirstSolutionStrategy.Types.Value.PathCheapestArc;
    // [END parameters]

    // Solve the problem.
    // [START solve]
    Assignment solution = routing.SolveWithParameters(searchParameters);
    // [END solve]

    // Print solution on console.
    // [START print_solution]
    PrintSolution(routing, manager, solution);
    // [END print_solution]
  }
}
// [END program]