133 lines
3.9 KiB
Java
133 lines
3.9 KiB
Java
// Copyright 2011 Hakan Kjellerstrand hakank@gmail.com
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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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import java.io.*;
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import java.util.*;
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import java.text.*;
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import com.google.ortools.constraintsolver.DecisionBuilder;
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import com.google.ortools.constraintsolver.IntVar;
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import com.google.ortools.constraintsolver.Solver;
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import com.google.ortools.constraintsolver.OptimizeVar;
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public class CoveringOpl {
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static {
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System.loadLibrary("jniortools");
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}
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/**
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*
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* Solves a set covering problem.
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* See http://www.hakank.org/google_or_tools/covering_opl.py
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*
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*/
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private static void solve() {
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Solver solver = new Solver("CoveringOpl");
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//
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// data
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//
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int num_workers = 32;
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int num_tasks = 15;
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// Which worker is qualified for each task.
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// Note: This is 1-based and will be made 0-base below.
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int[][] qualified = {{ 1, 9, 19, 22, 25, 28, 31 },
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{ 2, 12, 15, 19, 21, 23, 27, 29, 30, 31, 32 },
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{ 3, 10, 19, 24, 26, 30, 32 },
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{ 4, 21, 25, 28, 32 },
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{ 5, 11, 16, 22, 23, 27, 31 },
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{ 6, 20, 24, 26, 30, 32 },
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{ 7, 12, 17, 25, 30, 31 } ,
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{ 8, 17, 20, 22, 23 },
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{ 9, 13, 14, 26, 29, 30, 31 },
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{ 10, 21, 25, 31, 32 },
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{ 14, 15, 18, 23, 24, 27, 30, 32 },
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{ 18, 19, 22, 24, 26, 29, 31 },
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{ 11, 20, 25, 28, 30, 32 },
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{ 16, 19, 23, 31 },
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{ 9, 18, 26, 28, 31, 32 }};
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int[] cost = {1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 3,
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3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 8, 9};
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//
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// variables
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//
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IntVar[] hire = solver.makeIntVarArray(num_workers, 0, 1, "workers");
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IntVar total_cost = solver.makeScalProd(hire, cost).var();
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//
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// constraints
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//
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for(int j = 0; j < num_tasks; j++) {
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// Sum the cost for hiring the qualified workers
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// (also, make 0-base).
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int len = qualified[j].length;
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IntVar[] tmp = new IntVar[len];
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for(int c = 0; c < len; c++) {
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tmp[c] = hire[qualified[j][c] - 1];
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}
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IntVar b = solver.makeSum(tmp).var();
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solver.addConstraint(solver.makeGreaterOrEqual(b, 1));
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}
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// Objective: Minimize total cost
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OptimizeVar objective = solver.makeMinimize(total_cost, 1);
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//
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// search
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//
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DecisionBuilder db = solver.makePhase(hire,
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solver.CHOOSE_FIRST_UNBOUND,
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solver.ASSIGN_MIN_VALUE);
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solver.newSearch(db, objective);
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//
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// output
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//
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while (solver.nextSolution()) {
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System.out.println("Cost: " + total_cost.value());
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System.out.print("Hire: ");
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for(int i = 0; i < num_workers; i++) {
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if (hire[i].value() == 1) {
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System.out.print(i + " ");
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}
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}
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System.out.println("\n");
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}
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solver.endSearch();
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// Statistics
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System.out.println();
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System.out.println("Solutions: " + solver.solutions());
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System.out.println("Failures: " + solver.failures());
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System.out.println("Branches: " + solver.branches());
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System.out.println("Wall time: " + solver.wallTime() + "ms");
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}
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public static void main(String[] args) throws Exception {
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CoveringOpl.solve();
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}
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}
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