001 package aima.search.eightpuzzle;
002
003 import java.util.ArrayList;
004 import java.util.List;
005
006 import aima.basic.XYLocation;
007
008 /**
009 * @author Ravi Mohan
010 *
011 */
012
013 public class EightPuzzleBoard {
014
015 public static String LEFT = "Left";
016
017 public static String RIGHT = "Right";
018
019 public static String UP = "Up";
020
021 public static String DOWN = "Down";
022
023 public int[] getBoard() {
024 return board;
025 }
026
027 int[] board;
028
029 public EightPuzzleBoard() {
030 board = new int[] { 5, 4, 0, 6, 1, 8, 7, 3, 2 };
031
032 }
033
034 public EightPuzzleBoard(int[] aBoard) {
035 board = aBoard;
036 }
037
038 private int[] xycoordinatesFromAbsoluteCoordinate(int x) {
039 int[] retVal = null;
040 switch (x) {
041 case 0:
042 retVal = new int[] { 0, 0 };
043 break;
044 case 1:
045 retVal = new int[] { 0, 1 };
046 break;
047 case 2:
048 retVal = new int[] { 0, 2 };
049 break;
050 case 3:
051 retVal = new int[] { 1, 0 };
052 break;
053 case 4:
054 retVal = new int[] { 1, 1 };
055 break;
056 case 5:
057 retVal = new int[] { 1, 2 };
058 break;
059 case 6:
060 retVal = new int[] { 2, 0 };
061 break;
062 case 7:
063 retVal = new int[] { 2, 1 };
064 break;
065 case 8:
066 retVal = new int[] { 2, 2 };
067 break;
068
069 }
070 return retVal;
071 }
072
073 private int absoluteCoordinatesFromXYCoordinates(int x, int y) {
074 return x * 3 + y;
075 }
076
077 private int getValueAt(int x, int y) {
078 // refactor this use either case or a div/mod soln
079 return board[absoluteCoordinatesFromXYCoordinates(x, y)];
080 }
081
082 private int getGapPosition() {
083
084 return getPositionOf(0);
085 }
086
087 private int getPositionOf(int val) {
088 int retVal = -1;
089 for (int i = 0; i < 9; i++) {
090 if (board[i] == val) {
091 retVal = i;
092 }
093 }
094 return retVal;
095 }
096
097 public XYLocation getLocationOf(int val) {
098 int abspos = getPositionOf(val);
099 int xpos = xycoordinatesFromAbsoluteCoordinate(abspos)[0];
100 int ypos = xycoordinatesFromAbsoluteCoordinate(abspos)[1];
101 return new XYLocation(xpos, ypos);
102 }
103
104 private void setValue(int xPos, int yPos, int val) {
105 int abscoord = absoluteCoordinatesFromXYCoordinates(xPos, yPos);
106 board[abscoord] = val;
107
108 }
109
110 public int getValueAt(XYLocation loc) {
111 return getValueAt(loc.getXCoOrdinate(), loc.getYCoOrdinate());
112 }
113
114 public void moveGapRight() {
115 int gapPosition = getGapPosition();
116 int xpos = xycoordinatesFromAbsoluteCoordinate(gapPosition)[0];
117 int ypos = xycoordinatesFromAbsoluteCoordinate(gapPosition)[1];
118 if (!(ypos == 2)) {
119 int valueOnRight = getValueAt(xpos, ypos + 1);
120 setValue(xpos, ypos, valueOnRight);
121 setValue(xpos, ypos + 1, 0);
122 }
123
124 }
125
126 public void moveGapLeft() {
127 int gapPosition = getGapPosition();
128 int xpos = xycoordinatesFromAbsoluteCoordinate(gapPosition)[0];
129 int ypos = xycoordinatesFromAbsoluteCoordinate(getGapPosition())[1];
130 if (!(ypos == 0)) {
131 int valueOnLeft = getValueAt(xpos, ypos - 1);
132 setValue(xpos, ypos, valueOnLeft);
133 setValue(xpos, ypos - 1, 0);
134 }
135
136 }
137
138 public void moveGapDown() {
139 int gapPosition = getGapPosition();
140 int xpos = xycoordinatesFromAbsoluteCoordinate(gapPosition)[0];
141 int ypos = xycoordinatesFromAbsoluteCoordinate(gapPosition)[1];
142 if (!(xpos == 2)) {
143 int valueOnBottom = getValueAt(xpos + 1, ypos);
144 setValue(xpos, ypos, valueOnBottom);
145 setValue(xpos + 1, ypos, 0);
146 }
147
148 }
149
150 public void moveGapUp() {
151 int gapPosition = getGapPosition();
152 int xpos = xycoordinatesFromAbsoluteCoordinate(gapPosition)[0];
153 int ypos = xycoordinatesFromAbsoluteCoordinate(gapPosition)[1];
154 if (!(xpos == 0)) {
155 int valueOnTop = getValueAt(xpos - 1, ypos);
156 setValue(xpos, ypos, valueOnTop);
157 setValue(xpos - 1, ypos, 0);
158 }
159
160 }
161
162 @Override
163 public boolean equals(Object o) {
164
165 if (this == o) {
166 return true;
167 }
168 if ((o == null) || (this.getClass() != o.getClass())) {
169 return false;
170 }
171 EightPuzzleBoard aBoard = (EightPuzzleBoard) o;
172
173 for (int i = 0; i < 8; i++) {
174 if (this.getPositionOf(i) != aBoard.getPositionOf(i)) {
175 return false;
176 }
177 }
178 return true;
179 }
180
181 @Override
182 public int hashCode() {
183 int result = 17;
184 for (int i = 0; i < 8; i++) {
185 int position = this.getPositionOf(i);
186 result = 37 * result + position;
187 }
188 return result;
189 }
190
191 public List<XYLocation> getPositions() {
192 ArrayList<XYLocation> retVal = new ArrayList<XYLocation>();
193 for (int i = 0; i < 9; i++) {
194 int[] res = xycoordinatesFromAbsoluteCoordinate(getPositionOf(i));
195 XYLocation loc = new XYLocation(res[0], res[1]);
196 retVal.add(loc);
197
198 }
199 return retVal;
200 }
201
202 public void setBoard(List<XYLocation> locs) {
203
204 int count = 0;
205
206 for (int i = 0; i < locs.size(); i++) {
207 XYLocation loc = locs.get(i);
208 this.setValue(loc.getXCoOrdinate(), loc.getYCoOrdinate(), count);
209 count = count + 1;
210 }
211 }
212
213 public boolean canMoveGap(String where) {
214 boolean retVal = true;
215 int absPos = getPositionOf(0);
216 if (where.equals(LEFT)) {
217 if ((absPos == 0) || (absPos == 3) || (absPos == 6)) {
218 retVal = false;
219 }
220 }
221 if (where.equals(RIGHT)) {
222 if ((absPos == 2) || (absPos == 5) || (absPos == 8)) {
223 retVal = false;
224 }
225 }
226 if (where.equals(UP)) {
227 if ((absPos == 0) || (absPos == 1) || (absPos == 2)) {
228 retVal = false;
229 }
230 }
231 if (where.equals(DOWN)) {
232 if ((absPos == 6) || (absPos == 7) || (absPos == 8)) {
233 retVal = false;
234 }
235 }
236
237 return retVal;
238 }
239
240 @Override
241 public String toString() {
242 String retVal = board[0] + " " + board[1] + " " + board[2] + "\n"
243 + board[3] + " " + board[4] + " " + board[5] + " " + "\n"
244 + board[6] + " " + board[7] + " " + board[8];
245 return retVal;
246 }
247
248 }