VrpWithTimeLimit.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;
using Google.Protobuf.WellKnownTypes; // Duration
// [END import]

/// <summary>
///   Minimal Vrp using a time limit.
/// </summary>
public class Vrp {
  // [START solution_printer]
  /// <summary>
  ///   Print the solution.
  /// </summary>
  static void PrintSolution(
      in RoutingIndexManager manager,
      in RoutingModel routing,
      in Assignment solution) {
    // Inspect solution.
    long maxRouteDistance = 0;
    for (int i = 0; i < manager.GetNumberOfVehicles(); ++i) {
      Console.WriteLine("Route for Vehicle {0}:", i);
      long routeDistance = 0;
      var index = routing.Start(i);
      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("Distance of the route: {0}m", routeDistance);
      maxRouteDistance = Math.Max(routeDistance, maxRouteDistance);
    }
    Console.WriteLine("Maximum distance of the routes: {0}m", maxRouteDistance);
  }
  // [END solution_printer]

  public static void Main(String[] args) {
    // Instantiate the data problem.
    // [START data]
    int locationNumber = 20;
    int vehicleNumber = 5;
    int depot = 0;
    // [END data]

    // Create Routing Index Manager
    // [START index_manager]
    RoutingIndexManager manager = new RoutingIndexManager(
        locationNumber,
        vehicleNumber,
        depot);

    // [END index_manager]

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

    // Create and register a transit callback.
    // [START transit_callback]
    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 1; }
        );
    // [END transit_callback]

    // Define cost of each arc.
    // [START arc_cost]
    routing.SetArcCostEvaluatorOfAllVehicles(transitCallbackIndex);
    // [END arc_cost]

    // Add Distance constraint.
    // [START distance_constraint]
    routing.AddDimension(
        transitCallbackIndex,
        /*slack=*/0,
        /*horizon=*/3000,
        /*start_cumul_to_zero=*/true,
        "Distance");
    RoutingDimension distanceDimension = routing.GetMutableDimension("Distance");
    distanceDimension.SetGlobalSpanCostCoefficient(100);
    // [END distance_constraint]

    // Setting first solution heuristic.
    // [START parameters]
    RoutingSearchParameters searchParameters =
      operations_research_constraint_solver.DefaultRoutingSearchParameters();
    searchParameters.FirstSolutionStrategy = FirstSolutionStrategy.Types.Value.PathCheapestArc;
    searchParameters.LocalSearchMetaheuristic = LocalSearchMetaheuristic.Types.Value.GuidedLocalSearch;
    searchParameters.LogSearch = true;
    searchParameters.TimeLimit = new Duration { Seconds = 10 };
    // [END parameters]

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

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