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EggCartonNode.java
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EggCartonNode.java
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import java.util.ArrayList;
import java.util.Arrays;
import java.util.Random;
/**
* Specialized class for the Egg Carton Puzzle
* @author Torgeir, Olav
*
*/
public class EggCartonNode extends Node{
private static final int UP = 0;
private static final int DOWN = 2;
//representation of the eggs in this node
private boolean[][] eggs;
public EggCartonNode(Board board) {
super(board);
eggs = new boolean[board.getRows()][board.getColumns()];
}
public EggCartonNode(Board board, boolean[][] eggs) {
this(board);
this.eggs = eggs;
}
/**
* generates all neighbours to this node by moving one egg up or down one coordinate.
* One movement = one new neighbour
*/
public ArrayList<Node> generateNeighbours() {
ArrayList<Node> neighbours = new ArrayList<Node>();;
//loops through the board and makes a neighbour of every legal egg-move
for (int i = 0; i < board.getColumns(); i++) {
for (int j = 0; j < board.getRows(); j++) {
if (eggs[j][i]) {
if (isLegalMove(i, j, UP)) {
neighbours.add(new EggCartonNode(board, cloneArrayAndMakeNeighbour(eggs, i, j, UP)));
}
if (isLegalMove(i, j, DOWN)) {
neighbours.add(new EggCartonNode(board, cloneArrayAndMakeNeighbour(eggs, i, j, DOWN)));
}
}
}
}
return neighbours;
}
/**
* Makes a copy of the eggs-array that reflects the movement of an egg
* @param src Old array
* @param oldX Position of the egg to be moved
* @param oldY Position of the egg to be moved
* @param direction The direction the egg should be moved
* @return Updated Array
*/
private static boolean[][] cloneArrayAndMakeNeighbour(boolean[][] src, int oldX, int oldY, int direction) {
int length = src.length;
boolean[][] target = new boolean[length][src[0].length];
for (int i = 0; i < length; i++) {
System.arraycopy(src[i], 0, target[i], 0, src[i].length);
}
target[oldY][oldX] = false;
if (direction == UP) {
target[oldY - 1][oldX] = true;
}
else if (direction == DOWN) {
target[oldY + 1][oldX] = true;
}
return target;
}
/**
* Objective function. Each egg that satisfies the constraints gets a point
* @return double from 0.0 - 1.0 based on the correctness of this node
*/
public double evaluate() {
int r = board.getRows();
int c = board.getColumns();
int k = board.getK();
//Arrays used to check each directional constraint
int[] rowK = new int[c];
int[] colK = new int[r];
int[] diagLeftK = new int[r + c - 1];
int[] diagRightK = new int[r + c - 1];
double heuristic = 0;
//Sets up the constraints by accumulating eggs in each row/column/diagonals
for (int y = 0; y < r; y ++) {
for (int x = 0; x < c; x ++) {
if (eggs[y][x]) {
rowK[y] ++;
colK[x] ++;
int indexDiagRight = c - x + y - 1;
int indexDiagLeft = x + y;
diagRightK[indexDiagRight] ++;
diagLeftK[indexDiagLeft] ++;
}
}
}
//each egg is tested against the constraints. If the constraints are met, the egg generates a point
for (int y = 0; y < r; y++) {
for (int x = 0; x < c; x++) {
if (eggs[y][x]) {
int indexDiagRight = c - x + y - 1;
int indexDiagLeft = x + y;
if ((rowK[y] <= k) && (colK[x] <= k) && (diagRightK[indexDiagRight] <= k) &&
(diagLeftK[indexDiagLeft] <= k)) {
heuristic++;
}
}
}
}
//Accumulated points is divided by boardsize*allowed eggs in each row/col/diagonal to get a double ranging from 0.0 - 1.0
return heuristic / (r * k);
}
/**
* Creates a random starting state by adding k eggs in each column
*/
public void makeThisTheInititalNode() {
Random r = new Random();
for (int i = 0; i < board.getColumns(); i++) {
int counter = 0;
while(counter < board.getK()) {
int row = r.nextInt(board.getRows());
if (!eggs[row][i]) {
eggs[row][i] = true;
counter++;
}
}
}
}
/**
* Checks if a move is legal. I.e an egg should not be moved out of the board or on top of another egg
* @param x Position of egg
* @param y Position of egg
* @param direction Direction it wants to move
* @return If the move is legal
*/
private boolean isLegalMove(int x, int y, int direction) {
if ((direction == UP) && (y-1 >= 0) && (!eggs[y-1][x])) return true;
else if ((direction == DOWN) && (y + 1 < board.getRows()) && (!eggs[y+1][x])) return true;
return false;
}
public String toString() {
String res = "";
for (int y = 0; y < board.getRows(); y++) {
for (int x = 0; x < board.getRows(); x++) {
if (eggs[y][x]) {
res += "# ";
}
else {
res += "- ";
}
}
res += "\n";
}
return res;
}
}