organize_day_intervals.cs

// Copyright 2010-2021 Google LLC
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

using System;
using System.Collections;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
using Google.OrTools.ConstraintSolver;

public class OrganizeDay
{
    /**
     *
     *
     * Organizing a day.
     *
     * Simple scheduling problem.
     *
     * Problem formulation from ECLiPSe:
     * Slides on (Finite Domain) Constraint Logic Programming, page 38f
     * http://eclipseclp.org/reports/eclipse.ppt
     *
     *
     * Also see http://www.hakank.org/google_or_tools/organize_day.py
     *
     */
    private static void Solve()
    {
        Solver solver = new Solver("OrganizeDayIntervals");

        int n = 4;

        int work = 0;
        int mail = 1;
        int shop = 2;
        int bank = 3;
        // the valid times of the day
        int begin = 9;
        int end = 17;
        // tasks
        int[] tasks = { work, mail, shop, bank };
        // durations
        int[] durations = { 4, 1, 2, 1 };
        // Arrays for interval variables.
        int[] starts_max = { begin, begin, begin, begin };
        int[] ends_max = { end - 4, end - 1, end - 2, end - 1 };

        // task [i,0] must be finished before task [i,1]
        int[,] before_tasks = { { bank, shop }, { mail, work } };

        //
        // Decision variables
        //
        IntervalVar[] intervals =
            solver.MakeFixedDurationIntervalVarArray(n, starts_max, ends_max, durations, false, "task");
        //
        // Constraints
        //
        DisjunctiveConstraint disjunctive = intervals.Disjunctive("Sequence");
        solver.Add(disjunctive);

        // specific constraints
        for (int t = 0; t < before_tasks.GetLength(0); t++)
        {
            int before = before_tasks[t, 0];
            int after = before_tasks[t, 1];
            solver.Add(intervals[after].StartsAfterEnd(intervals[before]));
        }

        solver.Add(intervals[work].StartsAfter(11));

        //
        // Search
        //
        SequenceVar var = disjunctive.SequenceVar();
        SequenceVar[] seq_array = new SequenceVar[] { var };
        DecisionBuilder db = solver.MakePhase(seq_array, Solver.SEQUENCE_DEFAULT);

        solver.NewSearch(db);

        while (solver.NextSolution())
        {
            foreach (int t in tasks)
            {
                Console.WriteLine(intervals[t].ToString());
            }
            Console.WriteLine();
        }

        Console.WriteLine("\nSolutions: {0}", solver.Solutions());
        Console.WriteLine("WallTime: {0}ms", solver.WallTime());
        Console.WriteLine("Failures: {0}", solver.Failures());
        Console.WriteLine("Branches: {0} ", solver.Branches());

        solver.EndSearch();
    }

    public static void Main(String[] args)
    {
        Solve();
    }
}