    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 * @author  Tomáš Müller
    024 * @version StudentSct 1.3 (Student Sectioning)<br>
    025 *          Copyright (C) 2007 - 2015 Tomáš Müller<br>
    026 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    027 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    028 * <br>
    029 *          This library is free software; you can redistribute it and/or modify
    030 *          it under the terms of the GNU Lesser General Public License as
    031 *          published by the Free Software Foundation; either version 3 of the
    032 *          License, or (at your option) any later version. <br>
    033 * <br>
    034 *          This library is distributed in the hope that it will be useful, but
    035 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    036 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    037 *          Lesser General Public License for more details. <br>
    038 * <br>
    039 *          You should have received a copy of the GNU Lesser General Public
    040 *          License along with this library; if not see
    041 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    042 */
    043public class AssignInitialSelection extends BranchBoundSelection {
    044
    045    public AssignInitialSelection(DataProperties properties) {
    046        super(properties);
    047    }
    048
    049    @Override
    050    public void init(Solver<Request, Enrollment> solver) {
    051        init(solver, "Assign initial enrollments...");
    052    }
    053
    054    @Override
    055    public Neighbour<Request, Enrollment> selectNeighbour(Solution<Request, Enrollment> solution) {
    056        Student student = null;
    057        while ((student = nextStudent()) != null) {
    058            Progress.getInstance(solution.getModel()).incProgress();
    059            if (student.nrAssignedRequests(solution.getAssignment()) > 0) continue;
    060            Neighbour<Request, Enrollment> neighbour = new InitialSelection(student, solution.getAssignment()).select();
    061            if (neighbour != null)
    062                return neighbour;
    063        }
    064        return null;
    065    }
    066
    067    public class InitialSelection extends Selection {
    068        public InitialSelection(Student student, Assignment<Request, Enrollment> assignment) {
    069            super(student, assignment);
    070        }
    071
    072        @Override
    073        public void backTrack(int idx) {
    074            if (iTimeout > 0 && (JProf.currentTimeMillis() - iT0) > iTimeout) {
    075                iTimeoutReached = true;
    076                return;
    077            }
    078            if (getBestAssignment() != null && getBound(idx) >= getBestValue()) {
    079                return;
    080            }
    081            if (idx == iAssignment.length) {
    082                if (getBestAssignment() == null || getValue() < getBestValue()) {
    083                    saveBest();
    084                }
    085                return;
    086            }
    087            Request request = iStudent.getRequests().get(idx);
    088            if (!canAssign(request, idx)) {
    089                backTrack(idx + 1);
    090                return;
    091            }
    092            if (request.isMPP()) {
    093                Enrollment initial = request.getInitialAssignment();
    094                if (initial != null) {
    095                    if (!inConflict(idx, initial)) {
    096                        iAssignment[idx] = initial;
    097                        backTrack(idx + 1);
    098                        iAssignment[idx] = null;
    099                    }
    100                } else {
    101                    backTrack(idx + 1);
    102                }
    103            } else {
    104                backTrack(idx + 1);
    105            }
    106        }
    107    }
    108}