206 lines
8.2 KiB
Java
206 lines
8.2 KiB
Java
// 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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package com.google.ortools.constraintsolver.samples;
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// [START import]
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import com.google.ortools.Loader;
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import com.google.ortools.constraintsolver.Assignment;
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import com.google.ortools.constraintsolver.FirstSolutionStrategy;
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import com.google.ortools.constraintsolver.LocalSearchMetaheuristic;
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import com.google.ortools.constraintsolver.RoutingDimension;
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import com.google.ortools.constraintsolver.RoutingIndexManager;
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import com.google.ortools.constraintsolver.RoutingModel;
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import com.google.ortools.constraintsolver.RoutingSearchParameters;
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import com.google.ortools.constraintsolver.main;
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import com.google.protobuf.Duration;
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import java.util.logging.Logger;
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// [END import]
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/** Minimal VRP. */
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public final class VrpSolutionCallback {
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private static final Logger logger = Logger.getLogger(VrpSolutionCallback.class.getName());
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// [START data_model]
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static class DataModel {
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public final 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 final int vehicleNumber = 4;
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public final 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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/// @brief Print the solution.
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static void printSolution(RoutingIndexManager routingManager, RoutingModel routingModel) {
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// Solution cost.
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logger.info("################");
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logger.info("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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if (routingModel.activeVehicleVar(i).value() == 0) {
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continue;
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}
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logger.info("Route for Vehicle " + i + ":");
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long routeDistance = 0;
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long index = routingModel.start(i);
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String route = "";
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while (!routingModel.isEnd(index)) {
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route += 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, i);
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}
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logger.info(route + routingManager.indexToNode(index));
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logger.info("Distance of the route: " + routeDistance + "m");
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totalDistance += routeDistance;
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}
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logger.info("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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static class SolutionCallback implements Runnable {
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public final long[] objectives;
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private final RoutingIndexManager routingManager;
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private final RoutingModel routingModel;
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private final int maxSolution;
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private int counter;
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public SolutionCallback(
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final RoutingIndexManager manager, final RoutingModel routing, int limit) {
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routingManager = manager;
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routingModel = routing;
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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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@Override
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public void run() {
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long objective = routingModel.costVar().value();
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if (counter == 0 || objective < objectives[counter - 1]) {
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objectives[counter] = objective;
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printSolution(routingManager, routingModel);
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counter++;
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}
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if (counter >= maxSolution) {
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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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Loader.loadNativeLibraries();
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// Instantiate the data problem.
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// [START data]
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final 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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final RoutingIndexManager routingManager =
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new RoutingIndexManager(data.distanceMatrix.length, 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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final 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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final int transitCallbackIndex =
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routingModel.registerTransitCallback((long fromIndex, long toIndex) -> {
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// Convert from routing variable Index to user NodeIndex.
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int fromNode = routingManager.indexToNode(fromIndex);
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int 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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boolean unused = 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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final SolutionCallback solutionCallback =
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new SolutionCallback(routingManager, routingModel, 15);
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routingModel.addAtSolutionCallback(solutionCallback);
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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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main.defaultRoutingSearchParameters()
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.toBuilder()
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.setFirstSolutionStrategy(FirstSolutionStrategy.Value.PATH_CHEAPEST_ARC)
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.setLocalSearchMetaheuristic(LocalSearchMetaheuristic.Value.GUIDED_LOCAL_SEARCH)
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.setTimeLimit(Duration.newBuilder().setSeconds(5).build())
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.build();
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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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logger.info(
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"Best objective: " + solutionCallback.objectives[solutionCallback.objectives.length - 1]);
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} else {
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logger.info("No solution found !");
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}
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// [END print_solution]
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}
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private VrpSolutionCallback() {}
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}
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// [END program]
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