207 lines
8.7 KiB
C#
207 lines
8.7 KiB
C#
// Copyright 2010-2025 Google LLC
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// [START program]
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// [START import]
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using System;
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using System.Collections.Generic;
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using Google.OrTools.ConstraintSolver;
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using Google.Protobuf.WellKnownTypes; // Duration
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// [END import]
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/// <summary>
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/// Minimal Vehicle Routing Problem (VRP).
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/// The search stop after improving the solution 15 times or after 5 seconds.
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/// </summary>
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public class VrpSolutionCallback
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{
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// [START data_model]
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class DataModel
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{
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public long[,] DistanceMatrix = {
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{ 0, 548, 776, 696, 582, 274, 502, 194, 308, 194, 536, 502, 388, 354, 468, 776, 662 },
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{ 548, 0, 684, 308, 194, 502, 730, 354, 696, 742, 1084, 594, 480, 674, 1016, 868, 1210 },
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{ 776, 684, 0, 992, 878, 502, 274, 810, 468, 742, 400, 1278, 1164, 1130, 788, 1552, 754 },
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{ 696, 308, 992, 0, 114, 650, 878, 502, 844, 890, 1232, 514, 628, 822, 1164, 560, 1358 },
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{ 582, 194, 878, 114, 0, 536, 764, 388, 730, 776, 1118, 400, 514, 708, 1050, 674, 1244 },
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{ 274, 502, 502, 650, 536, 0, 228, 308, 194, 240, 582, 776, 662, 628, 514, 1050, 708 },
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{ 502, 730, 274, 878, 764, 228, 0, 536, 194, 468, 354, 1004, 890, 856, 514, 1278, 480 },
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{ 194, 354, 810, 502, 388, 308, 536, 0, 342, 388, 730, 468, 354, 320, 662, 742, 856 },
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{ 308, 696, 468, 844, 730, 194, 194, 342, 0, 274, 388, 810, 696, 662, 320, 1084, 514 },
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{ 194, 742, 742, 890, 776, 240, 468, 388, 274, 0, 342, 536, 422, 388, 274, 810, 468 },
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{ 536, 1084, 400, 1232, 1118, 582, 354, 730, 388, 342, 0, 878, 764, 730, 388, 1152, 354 },
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{ 502, 594, 1278, 514, 400, 776, 1004, 468, 810, 536, 878, 0, 114, 308, 650, 274, 844 },
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{ 388, 480, 1164, 628, 514, 662, 890, 354, 696, 422, 764, 114, 0, 194, 536, 388, 730 },
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{ 354, 674, 1130, 822, 708, 628, 856, 320, 662, 388, 730, 308, 194, 0, 342, 422, 536 },
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{ 468, 1016, 788, 1164, 1050, 514, 514, 662, 320, 274, 388, 650, 536, 342, 0, 764, 194 },
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{ 776, 868, 1552, 560, 674, 1050, 1278, 742, 1084, 810, 1152, 274, 388, 422, 764, 0, 798 },
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{ 662, 1210, 754, 1358, 1244, 708, 480, 856, 514, 468, 354, 844, 730, 536, 194, 798, 0 }
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};
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public int VehicleNumber = 4;
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public int Depot = 0;
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};
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// [END data_model]
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// [START solution_callback_printer]
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/// <summary>
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/// Print the solution.
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/// </summary>
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static void printSolution(ref RoutingIndexManager routingManager, ref RoutingModel routingModel)
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{
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Console.WriteLine($"Solution objective: {routingModel.CostVar().Value()}:");
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// Inspect solution.
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long totalDistance = 0;
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for (int i = 0; i < routingManager.GetNumberOfVehicles(); ++i)
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{
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Console.WriteLine("################");
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Console.WriteLine($"Route for Vehicle {i}:");
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long routeDistance = 0;
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long index = routingModel.Start(i);
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if (routingModel.IsEnd(routingModel.NextVar(index).Value()))
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{
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continue;
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}
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while (routingModel.IsEnd(index) == false)
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{
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Console.Write($" {routingManager.IndexToNode(index)} ->");
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long previousIndex = index;
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index = routingModel.NextVar(index).Value();
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routeDistance += routingModel.GetArcCostForVehicle(previousIndex, index, 0);
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}
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Console.WriteLine($" {routingManager.IndexToNode(index)}");
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Console.WriteLine($"Distance of the route: {routeDistance}m");
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totalDistance += routeDistance;
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}
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Console.WriteLine($"Total Distance of all routes: {totalDistance}m");
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}
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// [END solution_callback_printer]
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// [START solution_callback]
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class SolutionCallback
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{
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public long[] objectives;
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private RoutingIndexManager routingManager;
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private RoutingModel routingModel;
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private long maxSolution;
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private long counter;
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public SolutionCallback(ref RoutingIndexManager manager, ref RoutingModel routing, in long limit)
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{
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routingManager = manager;
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routingModel = routing;
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;
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maxSolution = limit;
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counter = 0;
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objectives = new long[maxSolution];
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}
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public void Run()
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{
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long objective = routingModel.CostVar().Value();
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if (counter == 0 || objective < objectives[counter - 1])
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{
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objectives[counter] = objective;
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printSolution(ref routingManager, ref routingModel);
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counter++;
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}
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if (counter >= maxSolution)
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{
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routingModel.solver().FinishCurrentSearch();
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}
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}
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};
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// [END solution_callback]
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public static void Main(String[] args)
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{
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// Instantiate the data problem.
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// [START data]
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DataModel data = new DataModel();
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// [END data]
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// Create Routing Index Manager
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// [START index_manager]
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RoutingIndexManager routingManager =
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new RoutingIndexManager(data.DistanceMatrix.GetLength(0), data.VehicleNumber, data.Depot);
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// [END index_manager]
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// Create Routing Model.
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// [START routing_model]
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RoutingModel routingModel = new RoutingModel(routingManager);
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// [END routing_model]
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// Create and register a transit callback.
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// [START transit_callback]
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int transitCallbackIndex =
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routingModel.RegisterTransitCallback((long fromIndex, long toIndex) =>
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{
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// Convert from routing variable Index to
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// distance matrix NodeIndex.
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var fromNode = routingManager.IndexToNode(fromIndex);
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var toNode = routingManager.IndexToNode(toIndex);
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return data.DistanceMatrix[fromNode, toNode];
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});
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// [END transit_callback]
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// Define cost of each arc.
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// [START arc_cost]
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routingModel.SetArcCostEvaluatorOfAllVehicles(transitCallbackIndex);
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// [END arc_cost]
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// Add Distance constraint.
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// [START distance_constraint]
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routingModel.AddDimension(transitCallbackIndex,
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0, // no slack
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3000, // vehicle maximum travel distance
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true, // start cumul to zero
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"Distance");
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RoutingDimension distanceDimension = routingModel.GetMutableDimension("Distance");
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distanceDimension.SetGlobalSpanCostCoefficient(100);
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// [END distance_constraint]
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// Attach a solution callback.
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// [START attach_callback]
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SolutionCallback solutionCallback =
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new SolutionCallback(ref routingManager, ref routingModel, /*max_solution=*/15);
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routingModel.AddAtSolutionCallback(solutionCallback.Run);
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// [END attach_callback]
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// Setting first solution heuristic.
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// [START parameters]
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RoutingSearchParameters searchParameters =
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operations_research_constraint_solver.DefaultRoutingSearchParameters();
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searchParameters.FirstSolutionStrategy = FirstSolutionStrategy.Types.Value.PathCheapestArc;
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searchParameters.LocalSearchMetaheuristic = LocalSearchMetaheuristic.Types.Value.GuidedLocalSearch;
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searchParameters.TimeLimit = new Duration { Seconds = 5 };
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// [END parameters]
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// Solve the problem.
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// [START solve]
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Assignment solution = routingModel.SolveWithParameters(searchParameters);
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// [END solve]
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// Print solution on console.
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// [START print_solution]
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if (solution != null)
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{
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Console.WriteLine($"Best objective: {solutionCallback.objectives[^1]}");
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}
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else
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{
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Console.WriteLine("No solution found !");
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}
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// [END print_solution]
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}
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}
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// [END program]
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