122 lines
3.6 KiB
Java
122 lines
3.6 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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package com.google.ortools.contrib;
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import com.google.ortools.Loader;
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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.OptimizeVar;
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import com.google.ortools.constraintsolver.Solver;
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import java.io.*;
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import java.text.*;
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import java.util.*;
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public class CoveringOpl {
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/** Solves a set covering problem. See http://www.hakank.org/google_or_tools/covering_opl.py */
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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 = {
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{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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};
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int[] cost = {
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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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//
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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 =
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solver.makePhase(hire, solver.CHOOSE_FIRST_UNBOUND, 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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Loader.loadNativeLibraries();
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CoveringOpl.solve();
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}
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}
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