103 lines
3.6 KiB
Java
103 lines
3.6 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 static java.lang.Math.abs;
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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 Routing example to showcase calling the solver.*/
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public class SimpleRoutingProgram {
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private static final Logger logger = Logger.getLogger(SimpleRoutingProgram.class.getName());
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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 int numLocation = 5;
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final int numVehicles = 1;
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final int depot = 0;
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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 = new RoutingIndexManager(numLocation, numVehicles, 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 abs(toNode - fromNode);
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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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logger.info("Objective: " + solution.objectiveValue());
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// Inspect solution.
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long index = routing.start(0);
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logger.info("Route for Vehicle 0:");
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long routeDistance = 0;
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String route = "";
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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(index);
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logger.info(route);
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logger.info("Distance of the route: " + routeDistance + "m");
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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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