c34026b101
note: done using ```sh git grep -l "2010-2024 Google" | xargs sed -i 's/2010-2024 Google/2010-2025 Google/' ```
124 lines
3.7 KiB
Java
124 lines
3.7 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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// CP-SAT example that solves an assignment problem.
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// [START program]
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package com.google.ortools.sat.samples;
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// [START import]
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import com.google.ortools.Loader;
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import com.google.ortools.sat.CpModel;
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import com.google.ortools.sat.CpSolver;
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import com.google.ortools.sat.CpSolverStatus;
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import com.google.ortools.sat.LinearExpr;
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import com.google.ortools.sat.LinearExprBuilder;
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import com.google.ortools.sat.Literal;
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import java.util.ArrayList;
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import java.util.List;
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import java.util.stream.IntStream;
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// [END import]
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/** Assignment problem. */
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public class AssignmentSat {
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public static void main(String[] args) {
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Loader.loadNativeLibraries();
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// Data
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// [START data_model]
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int[][] costs = {
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{90, 80, 75, 70},
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{35, 85, 55, 65},
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{125, 95, 90, 95},
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{45, 110, 95, 115},
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{50, 100, 90, 100},
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};
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final int numWorkers = costs.length;
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final int numTasks = costs[0].length;
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final int[] allWorkers = IntStream.range(0, numWorkers).toArray();
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final int[] allTasks = IntStream.range(0, numTasks).toArray();
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// [END data_model]
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// Model
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// [START model]
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CpModel model = new CpModel();
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// [END model]
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// Variables
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// [START variables]
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Literal[][] x = new Literal[numWorkers][numTasks];
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for (int worker : allWorkers) {
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for (int task : allTasks) {
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x[worker][task] = model.newBoolVar("x[" + worker + "," + task + "]");
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}
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}
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// [END variables]
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// Constraints
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// [START constraints]
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// Each worker is assigned to at most one task.
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for (int worker : allWorkers) {
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List<Literal> tasks = new ArrayList<>();
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for (int task : allTasks) {
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tasks.add(x[worker][task]);
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}
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model.addAtMostOne(tasks);
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}
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// Each task is assigned to exactly one worker.
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for (int task : allTasks) {
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List<Literal> workers = new ArrayList<>();
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for (int worker : allWorkers) {
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workers.add(x[worker][task]);
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}
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model.addExactlyOne(workers);
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}
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// [END constraints]
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// Objective
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// [START objective]
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LinearExprBuilder obj = LinearExpr.newBuilder();
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for (int worker : allWorkers) {
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for (int task : allTasks) {
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obj.addTerm(x[worker][task], costs[worker][task]);
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}
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}
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model.minimize(obj);
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// [END objective]
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// Solve
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// [START solve]
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CpSolver solver = new CpSolver();
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CpSolverStatus status = solver.solve(model);
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// [END solve]
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// Print solution.
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// [START print_solution]
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// Check that the problem has a feasible solution.
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if (status == CpSolverStatus.OPTIMAL || status == CpSolverStatus.FEASIBLE) {
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System.out.println("Total cost: " + solver.objectiveValue() + "\n");
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for (int i = 0; i < numWorkers; ++i) {
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for (int j = 0; j < numTasks; ++j) {
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if (solver.booleanValue(x[i][j])) {
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System.out.println(
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"Worker " + i + " assigned to task " + j + ". Cost: " + costs[i][j]);
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}
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}
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}
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} else {
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System.err.println("No solution found.");
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}
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// [END print_solution]
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}
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private AssignmentSat() {}
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}
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