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