1 // Copyright 2011 Hakan Kjellerstrand hakank@gmail.com 2 // Licensed under the Apache License, Version 2.0 (the "License"); 3 // you may not use this file except in compliance with the License. 4 // You may obtain a copy of the License at 5 // 6 // http://www.apache.org/licenses/LICENSE-2.0 7 // 8 // Unless required by applicable law or agreed to in writing, software 9 // distributed under the License is distributed on an "AS IS" BASIS, 10 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 11 // See the License for the specific language governing permissions and 12 // limitations under the License. 13 package com.google.ortools.contrib; 14 15 import com.google.ortools.Loader; 16 import com.google.ortools.constraintsolver.DecisionBuilder; 17 import com.google.ortools.constraintsolver.IntVar; 18 import com.google.ortools.constraintsolver.OptimizeVar; 19 import com.google.ortools.constraintsolver.Solver; 20 import java.io.*; 21 import java.text.*; 22 import java.util.*; 23 24 public class CoveringOpl { 25 /** Solves a set covering problem. See http://www.hakank.org/google_or_tools/covering_opl.py */ solve()26 private static void solve() { 27 Solver solver = new Solver("CoveringOpl"); 28 29 // 30 // data 31 // 32 int num_workers = 32; 33 int num_tasks = 15; 34 35 // Which worker is qualified for each task. 36 // Note: This is 1-based and will be made 0-base below. 37 int[][] qualified = {{1, 9, 19, 22, 25, 28, 31}, {2, 12, 15, 19, 21, 23, 27, 29, 30, 31, 32}, 38 {3, 10, 19, 24, 26, 30, 32}, {4, 21, 25, 28, 32}, {5, 11, 16, 22, 23, 27, 31}, 39 {6, 20, 24, 26, 30, 32}, {7, 12, 17, 25, 30, 31}, {8, 17, 20, 22, 23}, 40 {9, 13, 14, 26, 29, 30, 31}, {10, 21, 25, 31, 32}, {14, 15, 18, 23, 24, 27, 30, 32}, 41 {18, 19, 22, 24, 26, 29, 31}, {11, 20, 25, 28, 30, 32}, {16, 19, 23, 31}, 42 {9, 18, 26, 28, 31, 32}}; 43 44 int[] cost = {1, 1, 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 6, 45 6, 6, 7, 8, 9}; 46 47 // 48 // variables 49 // 50 IntVar[] hire = solver.makeIntVarArray(num_workers, 0, 1, "workers"); 51 IntVar total_cost = solver.makeScalProd(hire, cost).var(); 52 53 // 54 // constraints 55 // 56 for (int j = 0; j < num_tasks; j++) { 57 // Sum the cost for hiring the qualified workers 58 // (also, make 0-base). 59 int len = qualified[j].length; 60 IntVar[] tmp = new IntVar[len]; 61 for (int c = 0; c < len; c++) { 62 tmp[c] = hire[qualified[j][c] - 1]; 63 } 64 IntVar b = solver.makeSum(tmp).var(); 65 solver.addConstraint(solver.makeGreaterOrEqual(b, 1)); 66 } 67 68 // Objective: Minimize total cost 69 OptimizeVar objective = solver.makeMinimize(total_cost, 1); 70 71 // 72 // search 73 // 74 DecisionBuilder db = 75 solver.makePhase(hire, solver.CHOOSE_FIRST_UNBOUND, solver.ASSIGN_MIN_VALUE); 76 77 solver.newSearch(db, objective); 78 79 // 80 // output 81 // 82 while (solver.nextSolution()) { 83 System.out.println("Cost: " + total_cost.value()); 84 System.out.print("Hire: "); 85 for (int i = 0; i < num_workers; i++) { 86 if (hire[i].value() == 1) { 87 System.out.print(i + " "); 88 } 89 } 90 System.out.println("\n"); 91 } 92 93 solver.endSearch(); 94 95 // Statistics 96 System.out.println(); 97 System.out.println("Solutions: " + solver.solutions()); 98 System.out.println("Failures: " + solver.failures()); 99 System.out.println("Branches: " + solver.branches()); 100 System.out.println("Wall time: " + solver.wallTime() + "ms"); 101 } 102 main(String[] args)103 public static void main(String[] args) throws Exception { 104 Loader.loadNativeLibraries(); 105 CoveringOpl.solve(); 106 } 107 } 108