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PathsTree.java
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PathsTree.java
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/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
/**
*
* @author Ragha
*/
import java.util.ArrayList;
public class PathsTree {
private PathsTreeNode root;
/**
* Initializes an empty tree
*/
public PathsTree() {
this.root = null;
}
/**
* Initializes a tree starting at position (0, 0) of Chessboard chessboard
*/
public PathsTree(Chessboard chessboard) {
this.root = new PathsTreeNode(chessboard, new ChessboardPosition(0, 0, null));
}
/**
* Initializes a tree with root at position pos of Chessboard chessboard
*/
public PathsTree(Chessboard chessboard, ChessboardPosition pos) {
this.root = new PathsTreeNode(chessboard, pos);
}
public void print() {
print(0);
}
private void print(int indent) {
if (root == null) {
return;
}
for (int i = 0; i < indent; i++) {
System.out.print(" ");
}
System.out.println(root.pos);
for (PathsTree node : root.children) {
node.print(indent + 2);
}
}
public ArrayList<DLLPath> findAllPaths() {
ArrayList<DLLPath> paths = new ArrayList<DLLPath>();
return findAllPaths(paths);
}
public ArrayList<DLLPath> findAllPaths(ArrayList<DLLPath> paths) {
if(root.chessboard.getPosStatus(root.pos)==ChessboardStatus.GOAL){
DLLPath newpath = new DLLPath();
ChessboardPosition From = root.pos;
while(From!=null){
int row = From.getCoords()[0];
int col = From.getCoords()[1];
newpath.addFirst(row,col);
From = From.getFrom();
}
paths.add(newpath);
return paths;
}
for (PathsTree subtree : root.children){
ArrayList<DLLPath> path= subtree.findAllPaths();
for(int i=0;i<path.size();i++){
DLLPath newpath = path.get(i);
paths.add(newpath);
}
}
return paths;
//--------------------------------------
/* for(int i=0;i<root.children.size();i++){
PathsTree obj = root.children.get(i);
if(obj.root.chessboard.getPosStatus(obj.root.pos)==ChessboardStatus.GOAL){
DLLPath newpath = new DLLPath();
ChessboardPosition From = obj.root.pos;
while(From!=null){
int row = From.getCoords()[0];
int col = From.getCoords()[1];
newpath.addFirst(row,col);
From = From.getFrom();
}
paths.add(newpath);
}
}
return paths;*/
//-----------------------------
/* Task #4b: Finding all paths
*
* - This method should return all the valid paths as a DLLPath objects in the ArrayList.
*
*/
// Write your code here..
// return null; // TO DO: modify appropriately
}
/**
* Models each node in the paths tree Contains the position of the current
* step and references to the next possible steps
*/
private class PathsTreeNode {
private Chessboard chessboard;
private ChessboardPosition pos;
private ArrayList<PathsTree> children;
PathsTreeNode(Chessboard chessboard, ChessboardPosition pos) {
this.chessboard = chessboard;
this.pos = pos;
this.children = new ArrayList<PathsTree>();
this.exploreAllChildren();
}
void exploreAllChildren() {
if(chessboard.getPosStatus(pos)==ChessboardStatus.GOAL)
return;
ChessboardPosition Lpos = chessboard.getNeighbour(pos, Move.LEFT);
ChessboardPosition Upos = chessboard.getNeighbour(pos, Move.UP);
ChessboardPosition Rpos = chessboard.getNeighbour(pos, Move.RIGHT);
ChessboardPosition Dpos = chessboard.getNeighbour(pos, Move.DOWN);
if(Lpos!=null && chessboard.getPosStatus(Lpos)!=ChessboardStatus.OBSTACLE && this.isAncestor(Lpos)==false){
PathsTree obj = new PathsTree(chessboard,Lpos);
children.add(obj);
}
if(Upos!=null && chessboard.getPosStatus(Upos)!=ChessboardStatus.OBSTACLE && this.isAncestor(Upos)==false){
PathsTree obj = new PathsTree(chessboard,Upos);
children.add(obj);
}
if(Rpos!=null && chessboard.getPosStatus(Rpos)!=ChessboardStatus.OBSTACLE && this.isAncestor(Rpos)==false){
PathsTree obj = new PathsTree(chessboard,Rpos);
children.add(obj);
}
if(Dpos!=null && chessboard.getPosStatus(Dpos)!=ChessboardStatus.OBSTACLE && this.isAncestor(Dpos)==false){
PathsTree obj = new PathsTree(chessboard,Dpos);
children.add(obj);
}
/* Task #4a: Explore all children
*
* - This method should explore all children of a PathsTreeNode.
* - Moves priority: {LEFT, UP, RIGHT, DOWN}
* - You can use Move.values() to get the moves.
* - This method will explore children and add them to 'children' ArrayList as a PathsTree.
* - If the child is OPEN then you should explore its children
* - If the child is GOAL then you should just add it to 'children' ArrayList as a PathsTree.
* - You shouldn't add a child to 'children' ArrayList if it's OBSTACLE or NULL
* - You shouldn't add a child to 'children' ArrayList if it's already added in the its parents path (You can use isAncestor() method to check)
*/
// Write your code here..
}
/**
* Checks whether pos is an ancestor of this
*/
boolean isAncestor(ChessboardPosition pos) {
boolean res = false;
ChessboardPosition p = this.pos;
while (p != null) {
if (p.equals(pos)) {
return true;
}
p = p.getFrom();
}
return res;
}
}
public static void main(String[] args){
PathsTree tree = new PathsTree(new Chessboard(ChessboardSamples.sChessboard1));
tree.print();
/*ArrayList<DLLPath> paths = tree.findAllPaths();
for(int i=0;i<paths.size();i++){
DLLPath obj = paths.get(i);
System.out.println(obj);
}*/
}
}