144 lines
4.4 KiB
C#
144 lines
4.4 KiB
C#
// Copyright 2010-2021 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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using System;
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using System.Collections;
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using System.Linq;
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using Google.OrTools.ConstraintSolver;
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public class FurnitureMovingIntervals
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{
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/**
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*
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* Moving furnitures (scheduling) problem in Google CP Solver.
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*
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* Marriott & Stukey: 'Programming with constraints', page 112f
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*
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* Also see http://www.hakank.org/or-tools/furniture_moving.py
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*
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*/
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private static void Solve()
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{
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Solver solver = new Solver("FurnitureMovingIntervals");
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const int n = 4;
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int[] durations = { 30, 10, 15, 15 };
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int[] demand = { 3, 1, 3, 2 };
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const int upper_limit = 160;
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const int max_num_workers = 5;
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//
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// Decision variables
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//
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IntervalVar[] tasks = new IntervalVar[n];
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for (int i = 0; i < n; ++i)
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{
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tasks[i] =
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solver.MakeFixedDurationIntervalVar(0, upper_limit - durations[i], durations[i], false, "task_" + i);
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}
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// Fillers that span the whole resource and limit the available
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// number of workers.
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IntervalVar[] fillers = new IntervalVar[max_num_workers];
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for (int i = 0; i < max_num_workers; ++i)
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{
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fillers[i] = solver.MakeFixedDurationIntervalVar(0, 0, upper_limit, true, "filler_" + i);
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}
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// Number of needed resources, to be minimized or constrained.
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IntVar num_workers = solver.MakeIntVar(0, max_num_workers, "num_workers");
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// Links fillers and num_workers.
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for (int i = 0; i < max_num_workers; ++i)
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{
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solver.Add((num_workers > i) + fillers[i].PerformedExpr() == 1);
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}
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// Creates makespan.
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IntVar[] ends = new IntVar[n];
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for (int i = 0; i < n; ++i)
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{
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ends[i] = tasks[i].EndExpr().Var();
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}
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IntVar end_time = ends.Max().VarWithName("end_time");
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//
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// Constraints
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//
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IntervalVar[] all_tasks = new IntervalVar[n + max_num_workers];
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int[] all_demands = new int[n + max_num_workers];
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for (int i = 0; i < n; ++i)
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{
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all_tasks[i] = tasks[i];
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all_demands[i] = demand[i];
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}
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for (int i = 0; i < max_num_workers; ++i)
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{
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all_tasks[i + n] = fillers[i];
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all_demands[i + n] = 1;
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}
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solver.Add(all_tasks.Cumulative(all_demands, max_num_workers, "workers"));
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//
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// Some extra constraints to play with
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//
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// all tasks must end within an hour
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// solver.Add(end_time <= 60);
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// All tasks should start at time 0
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// for(int i = 0; i < n; i++) {
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// solver.Add(tasks[i].StartAt(0));
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// }
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// limitation of the number of people
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// solver.Add(num_workers <= 3);
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solver.Add(num_workers <= 4);
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//
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// Objective
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//
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// OptimizeVar obj = num_workers.Minimize(1);
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OptimizeVar obj = end_time.Minimize(1);
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//
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// Search
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//
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DecisionBuilder db = solver.MakePhase(all_tasks, Solver.INTERVAL_DEFAULT);
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solver.NewSearch(db, obj);
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while (solver.NextSolution())
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{
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Console.WriteLine(num_workers.ToString() + ", " + end_time.ToString());
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for (int i = 0; i < n; i++)
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{
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Console.WriteLine("{0} (demand:{1})", tasks[i].ToString(), demand[i]);
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}
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Console.WriteLine();
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}
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Console.WriteLine("Solutions: {0}", solver.Solutions());
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Console.WriteLine("WallTime: {0} ms", solver.WallTime());
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Console.WriteLine("Failures: {0}", solver.Failures());
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Console.WriteLine("Branches: {0} ", solver.Branches());
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solver.EndSearch();
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}
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public static void Main(String[] args)
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{
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Solve();
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}
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}
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