132 lines
5.0 KiB
Java
132 lines
5.0 KiB
Java
// Copyright 2010-2024 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.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 java.util.logging.Logger;
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// [END import]
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/** Minimal TSP using distance matrix. */
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public class TspCities {
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private static final Logger logger = Logger.getLogger(TspCities.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, 2451, 713, 1018, 1631, 1374, 2408, 213, 2571, 875, 1420, 2145, 1972},
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{2451, 0, 1745, 1524, 831, 1240, 959, 2596, 403, 1589, 1374, 357, 579},
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{713, 1745, 0, 355, 920, 803, 1737, 851, 1858, 262, 940, 1453, 1260},
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{1018, 1524, 355, 0, 700, 862, 1395, 1123, 1584, 466, 1056, 1280, 987},
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{1631, 831, 920, 700, 0, 663, 1021, 1769, 949, 796, 879, 586, 371},
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{1374, 1240, 803, 862, 663, 0, 1681, 1551, 1765, 547, 225, 887, 999},
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{2408, 959, 1737, 1395, 1021, 1681, 0, 2493, 678, 1724, 1891, 1114, 701},
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{213, 2596, 851, 1123, 1769, 1551, 2493, 0, 2699, 1038, 1605, 2300, 2099},
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{2571, 403, 1858, 1584, 949, 1765, 678, 2699, 0, 1744, 1645, 653, 600},
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{875, 1589, 262, 466, 796, 547, 1724, 1038, 1744, 0, 679, 1272, 1162},
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{1420, 1374, 940, 1056, 879, 225, 1891, 1605, 1645, 679, 0, 1017, 1200},
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{2145, 357, 1453, 1280, 586, 887, 1114, 2300, 653, 1272, 1017, 0, 504},
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{1972, 579, 1260, 987, 371, 999, 701, 2099, 600, 1162, 1200, 504, 0},
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};
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public final int vehicleNumber = 1;
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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_printer]
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/// @brief Print the solution.
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static void printSolution(
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RoutingModel routing, RoutingIndexManager manager, Assignment solution) {
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// Solution cost.
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logger.info("Objective: " + solution.objectiveValue() + "miles");
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// Inspect solution.
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logger.info("Route:");
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long routeDistance = 0;
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String route = "";
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long index = routing.start(0);
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while (!routing.isEnd(index)) {
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route += manager.indexToNode(index) + " -> ";
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long previousIndex = index;
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index = solution.value(routing.nextVar(index));
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routeDistance += routing.getArcCostForVehicle(previousIndex, index, 0);
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}
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route += manager.indexToNode(routing.end(0));
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logger.info(route);
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logger.info("Route distance: " + routeDistance + "miles");
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}
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// [END solution_printer]
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public static void main(String[] args) throws Exception {
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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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RoutingIndexManager manager =
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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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RoutingModel routing = new RoutingModel(manager);
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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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routing.registerTransitCallback((long fromIndex, long toIndex) -> {
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// Convert from routing variable Index to user NodeIndex.
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int fromNode = manager.indexToNode(fromIndex);
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int toNode = manager.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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routing.setArcCostEvaluatorOfAllVehicles(transitCallbackIndex);
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// [END arc_cost]
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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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.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 = routing.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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printSolution(routing, manager, solution);
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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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