    001package org.cpsolver.coursett.criteria;
    002
    003import java.util.List;
    004
    005import org.cpsolver.coursett.Constants;
    006import org.cpsolver.coursett.constraint.RoomConstraint.RoomConstraintContext;
    007import org.cpsolver.coursett.model.Placement;
    008import org.cpsolver.coursett.model.TimeLocation;
    009import org.cpsolver.ifs.util.DataProperties;
    010
    011
    012/**
    013 * Useless half-hours. This criterion counts cases when there is an empty half hour in a room.
    014 * Such half-hours should be generally avoided as usually any class takes more than half an hour.
    015 * <br>
    016 *
    017 * @author  Tomáš Müller
    018 * @version CourseTT 1.3 (University Course Timetabling)<br>
    019 *          Copyright (C) 2006 - 2014 Tomáš Müller<br>
    020 *          <a href="mailto:muller@unitime.org">muller@unitime.org</a><br>
    021 *          <a href="http://muller.unitime.org">http://muller.unitime.org</a><br>
    022 * <br>
    023 *          This library is free software; you can redistribute it and/or modify
    024 *          it under the terms of the GNU Lesser General Public License as
    025 *          published by the Free Software Foundation; either version 3 of the
    026 *          License, or (at your option) any later version. <br>
    027 * <br>
    028 *          This library is distributed in the hope that it will be useful, but
    029 *          WITHOUT ANY WARRANTY; without even the implied warranty of
    030 *          MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
    031 *          Lesser General Public License for more details. <br>
    032 * <br>
    033 *          You should have received a copy of the GNU Lesser General Public
    034 *          License along with this library; if not see
    035 *          <a href='http://www.gnu.org/licenses/'>http://www.gnu.org/licenses/</a>.
    036 */
    037public class UselessHalfHours extends BrokenTimePatterns {
    038
    039    @Override
    040    public double getWeightDefault(DataProperties config) {
    041        return Constants.sPreferenceLevelStronglyDiscouraged * config.getPropertyDouble("Comparator.UselessSlotWeight", 0.1);
    042    }
    043
    044    @Override
    045    public String getPlacementSelectionWeightName() {
    046        return "Placement.UselessSlotsWeight";
    047    }
    048
    049    @Override
    050    protected double penalty(RoomConstraintContext rc) {
    051        return countUselessSlotsHalfHours(rc);
    052    }
    053
    054    @Override
    055    protected double penalty(RoomConstraintContext rc, Placement value) {
    056        return countUselessSlotsHalfHours(rc, value);
    057    }
    058
    059    private static boolean isEmpty(RoomConstraintContext rc, int slot, Placement placement) {
    060        List<Placement> assigned = rc.getPlacements(slot);
    061        return assigned.isEmpty() || (placement != null && assigned.size() == 1 && assigned.get(0).variable().equals(placement.variable()));
    062    }
    063
    064
    065    private static boolean isUselessBefore(RoomConstraintContext rc, int slot, Placement placement) {
    066        int s = slot % Constants.SLOTS_PER_DAY;
    067        if (s - 1 < 0 || s + 6 >= Constants.SLOTS_PER_DAY)
    068            return false;
    069        return (!isEmpty(rc, slot - 1, placement) &&
    070                isEmpty(rc, slot + 0, placement) &&
    071                isEmpty(rc, slot + 1, placement) &&
    072                isEmpty(rc, slot + 2, placement) &&
    073                isEmpty(rc, slot + 3, placement) &&
    074                isEmpty(rc, slot + 4, placement) &&
    075                isEmpty(rc, slot + 5, placement) &&
    076                isEmpty(rc, slot + 6, placement));
    077    }
    078
    079    private static boolean isUselessAfter(RoomConstraintContext rc, int slot, Placement placement) {
    080        int s = slot % Constants.SLOTS_PER_DAY;
    081        if (s - 1 < 0 || s + 6 >= Constants.SLOTS_PER_DAY)
    082            return false;
    083        return (isEmpty(rc, slot - 1, placement) &&
    084                isEmpty(rc, slot + 0, placement) &&
    085                isEmpty(rc, slot + 1, placement) &&
    086                isEmpty(rc, slot + 2, placement) &&
    087                isEmpty(rc, slot + 3, placement) &&
    088                isEmpty(rc, slot + 4, placement) &&
    089                isEmpty(rc, slot + 5, placement) &&
    090                !isEmpty(rc, slot + 6, placement));
    091    }
    092
    093    private static boolean isUseless(RoomConstraintContext rc, int slot, Placement placement) {
    094        int s = slot % Constants.SLOTS_PER_DAY;
    095        if (s - 1 < 0 || s + 6 >= Constants.SLOTS_PER_DAY)
    096            return false;
    097        return (!isEmpty(rc, slot - 1, placement) &&
    098                isEmpty(rc, slot + 0, placement) &&
    099                isEmpty(rc, slot + 1, placement) &&
    100                isEmpty(rc, slot + 2, placement) &&
    101                isEmpty(rc, slot + 3, placement) &&
    102                isEmpty(rc, slot + 4, placement) &&
    103                isEmpty(rc, slot + 5, placement) &&
    104                !isEmpty(rc, slot + 6, placement));
    105    }
    106
    107    /** Number of useless half hours for this room
    108     * @param rc room constraint assignment context
    109     * @param placement placement that is being considered
    110     * @return number of useless slots caused by the given placement
    111     **/
    112    protected static int countUselessSlotsHalfHours(RoomConstraintContext rc, Placement placement) {
    113        int ret = 0;
    114        TimeLocation time = placement.getTimeLocation();
    115        int slot = time.getStartSlot() % Constants.SLOTS_PER_DAY;
    116        int days = time.getDayCode();
    117        for (int d = 0; d < Constants.NR_DAYS; d++) {
    118            if ((Constants.DAY_CODES[d] & days) == 0)
    119                continue;
    120            if (isUselessBefore(rc, d * Constants.SLOTS_PER_DAY + slot - 6, placement))
    121                ret ++;
    122            if (isUselessAfter(rc, d * Constants.SLOTS_PER_DAY + slot + time.getNrSlotsPerMeeting(), placement))
    123                ret ++;
    124            if (time.getNrSlotsPerMeeting() == 6 && isUseless(rc, d * Constants.SLOTS_PER_DAY + slot, placement))
    125                ret --;
    126        }
    127        return ret;
    128    }
    129
    130    private static boolean isUseless(RoomConstraintContext rc, int slot) {
    131        int s = slot % Constants.SLOTS_PER_DAY;
    132        if (s - 1 < 0 || s + 6 >= Constants.SLOTS_PER_DAY)
    133            return false;
    134        return (!rc.getPlacements(slot - 1).isEmpty() &&
    135                rc.getPlacements(slot + 0).isEmpty() &&
    136                rc.getPlacements(slot + 1).isEmpty() &&
    137                rc.getPlacements(slot + 2).isEmpty() &&
    138                rc.getPlacements(slot + 3).isEmpty() &&
    139                rc.getPlacements(slot + 4).isEmpty() &&
    140                rc.getPlacements(slot + 5).isEmpty() &&
    141                !rc.getPlacements(slot + 6).isEmpty());
    142    }
    143
    144    /** Number of useless slots for this room
    145     * @param rc room constraint assignment context
    146     * @return current penalty for the given room
    147     **/
    148    public static int countUselessSlotsHalfHours(RoomConstraintContext rc) {
    149        int ret = 0;
    150        for (int d = 0; d < Constants.NR_DAYS; d++) {
    151            for (int s = 0; s < Constants.SLOTS_PER_DAY; s++) {
    152                int slot = d * Constants.SLOTS_PER_DAY + s;
    153                if (isUseless(rc, slot))
    154                    ret++;
    155            }
    156        }
    157        return ret;
    158    }
    159}