    001package org.cpsolver.studentsct.heuristics.selection;
    002
    003import org.cpsolver.ifs.assignment.Assignment;
    004import org.cpsolver.ifs.model.Neighbour;
    005import org.cpsolver.ifs.solution.Solution;
    006import org.cpsolver.ifs.solver.Solver;
    007import org.cpsolver.ifs.util.DataProperties;
    008import org.cpsolver.ifs.util.JProf;
    009import org.cpsolver.ifs.util.Progress;
    010import org.cpsolver.studentsct.model.Enrollment;
    011import org.cpsolver.studentsct.model.Request;
    012import org.cpsolver.studentsct.model.Student;
    013
    014/**
    015 * Assign initial enrollments. An extension of {@link BranchBoundSelection},
    016 * where only initial enrollments (see {@link Request#getInitialAssignment()}) can
    017 * be assigned. Students that already has a schedule
    018 * ({@link Student#nrAssignedRequests(Assignment)} is greater then zero) are ignored.
    019 *
    020 * <br>
    021 * <br>
    022 *
    023 * @version StudentSct 1.3 (Student Sectioning)<br>
    024 *          Copyright (C) 2007 - 2015 Tomáš Müller<br>
    025 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    026 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    027 * <br>
    028 *          This library is free software; you can redistribute it and/or modify
    029 *          it under the terms of the GNU Lesser General Public License as
    030 *          published by the Free Software Foundation; either version 3 of the
    031 *          License, or (at your option) any later version. <br>
    032 * <br>
    033 *          This library is distributed in the hope that it will be useful, but
    034 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    035 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    036 *          Lesser General Public License for more details. <br>
    037 * <br>
    038 *          You should have received a copy of the GNU Lesser General Public
    039 *          License along with this library; if not see
    040 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    041 */
    042public class AssignInitialSelection extends BranchBoundSelection {
    043
    044    public AssignInitialSelection(DataProperties properties) {
    045        super(properties);
    046    }
    047
    048    @Override
    049    public void init(Solver<Request, Enrollment> solver) {
    050        init(solver, "Assign initial enrollments...");
    051    }
    052
    053    @Override
    054    public Neighbour<Request, Enrollment> selectNeighbour(Solution<Request, Enrollment> solution) {
    055        Student student = null;
    056        while ((student = nextStudent()) != null) {
    057            Progress.getInstance(solution.getModel()).incProgress();
    058            if (student.nrAssignedRequests(solution.getAssignment()) > 0) continue;
    059            Neighbour<Request, Enrollment> neighbour = new InitialSelection(student, solution.getAssignment()).select();
    060            if (neighbour != null)
    061                return neighbour;
    062        }
    063        return null;
    064    }
    065
    066    public class InitialSelection extends Selection {
    067        public InitialSelection(Student student, Assignment<Request, Enrollment> assignment) {
    068            super(student, assignment);
    069        }
    070
    071        @Override
    072        public void backTrack(int idx) {
    073            if (iTimeout > 0 && (JProf.currentTimeMillis() - iT0) > iTimeout) {
    074                iTimeoutReached = true;
    075                return;
    076            }
    077            if (getBestAssignment() != null && getBound(idx) >= getBestValue()) {
    078                return;
    079            }
    080            if (idx == iAssignment.length) {
    081                if (getBestAssignment() == null || getValue() < getBestValue()) {
    082                    saveBest();
    083                }
    084                return;
    085            }
    086            Request request = iStudent.getRequests().get(idx);
    087            if (!canAssign(request, idx)) {
    088                backTrack(idx + 1);
    089                return;
    090            }
    091            if (request.isMPP()) {
    092                Enrollment initial = request.getInitialAssignment();
    093                if (initial != null) {
    094                    if (!inConflict(idx, initial)) {
    095                        iAssignment[idx] = initial;
    096                        backTrack(idx + 1);
    097                        iAssignment[idx] = null;
    098                    }
    099                } else {
    100                    backTrack(idx + 1);
    101                }
    102            } else {
    103                backTrack(idx + 1);
    104            }
    105        }
    106    }
    107}