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Thread: Problem in recursion for Solving Maze Recursively program

  1. #1
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    Default Problem in recursion for Solving Maze Recursively program

    My program is to traverse through a maze and recursively search for '$' starting at element (1,1). I don't know if i'm running the recursion properly since my program skipps that there is a solid wall '&' and tests for it anyways. My traversable path is indicated by '#'.

    This is getting extremely annoying, any help will be very appreciated.

    import java.io.BufferedReader;
    import java.io.File;
    import java.io.FileNotFoundException;
    import java.io.FileReader;
    import java.io.IOException;
     
     
    public class Maze
    {
     
       public static char[][] slideData;
       private int ReturnCount = 0;
    	public Maze(String s)
    	{
    		try
    		{
    			File slideFile = new File(s);
    			FileReader in = new FileReader(slideFile);
    			BufferedReader readSlide = new BufferedReader(in);
    			int length = Integer.parseInt(readSlide.readLine());
    			int width = Integer.parseInt(readSlide.readLine());
    			slideData = new char[length][width];
     
    			for(int row = 0; row < length; row++){
    				for (int col = 0; col < width; col++){
    					slideData[row][col] = (char)readSlide.read();
    				}
    				readSlide.readLine();			
    				}
    			readSlide.close();
    			in.close();
    			}catch (FileNotFoundException e)
    			{
    				System.out.println("File does not exist/ could not be found.");
    				System.err.println("FileNotFoundException: " + e.getMessage());
    			}catch(IOException e){
    				System.out.println("Problem reading file.");
    					System.err.println("IOException: " + e.getMessage());	
    		}
    	}
     
     
    	public void displayColonies()
    	{
    		char[][] temp;
    		int count; 
     
    		for(int row = 0; row < slideData.length; row++)
    		{
    			for(int col = 0; col < slideData[0].length; col++)
    			{			
     
    				if(slideData[row][col] >= 0 )
    				{
    					count = getPath(row, col);
    					if(count != 0)
    					{
    					System.out.println("(" +row + "," + col + ") Cn"+ count);
    					}
    				}
    			}
    		}
    	}
     
     
     
     
    	public void displaySlide() {
     
    		char[][] temp;
    		int count = 0; 
    		if(count == 0)
    		{
    		System.out.println("Provided Slide:");
    		count++;
    		}
    		else
    			System.out.println("Ending Slide:");
     
    		for(int row = 0; row < slideData.length; row++){
    			for(int col = 0; col < slideData[0].length; col++){
    				System.out.print(slideData[row][col]);			
    			}
    			System.out.println();
    		}
     
    		System.out.println();
    	}
     
    private int getPath (int row, int col)
       {
          if (slideData[row][col] == '$')
          {
    	System.out.println("Maze found");
          return(0);
          }
          else
     
          {
          	if (slideData[row][col] == '#')
          {
             slideData[row][col] = '%';  // this cell has been tried
     
     
     
               if (slideData[row+1][col] == '#')
                {
                	slideData[row][col] = slideData[row+1][col];
                	slideData[row][col] = '%';
                	ReturnCount = ReturnCount+1;
                	ReturnCount = getPath(row +1, col);
                	System.out.println(ReturnCount);
                }
     
                if (slideData[row-1][col] == '#')
                {
                    slideData[row][col] = slideData[row-1][col];
                	slideData[row][col] = '%';
                	ReturnCount = ReturnCount+1;;
                	ReturnCount = getPath(row +1, col);
                	System.out.println(ReturnCount);
          }
     
               if (slideData[row][col-1] == '#')
                {
                	 slideData[row][col] = slideData[row][col-1];
                 	slideData[row][col] = '%';
                 	ReturnCount = ReturnCount+1;
                	ReturnCount = getPath(row +1, col);
                	System.out.println(ReturnCount);
                }
     
                if (slideData[row][col+1] == '#')
                {
                	 slideData[row][col] = slideData[row][col+1];
                 	slideData[row][col] = '%';
                 	ReturnCount = ReturnCount+1;
                	ReturnCount = getPath(row +1, col);
                	System.out.println(ReturnCount);
                }
     
          }
          }
     
          return ReturnCount ;
       }
     
     
     
       public static void main (String[] args)
       {
    		Maze culture = new Maze("Maze.txt");
    		culture.displaySlide();
    		culture.displayColonies();
    		culture.displaySlide();
     
       }
    }


    the Maze.txt slide..
    7
    9
    &&&&&&&&&
    &#&&&&&&&
    &######&&
    &#&&#&&&&
    &#&&$&&&&
    &#######&
    &&&&&&&&&


  2. #2
    Senile Half-Wit Freaky Chris's Avatar
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    Default Re: Solving Maze Recursively

    I've never done any map traversal before, so I thought i'd start from scratch and write my a version. It prints out the location of the finish at the end in terms of 0 based indexing for the array
    Hopefully you will be able to get an idea of where you are going wrong form this
    import java.io.FileNotFoundException;
    import java.io.FileReader;
    import java.util.Scanner;
     
    public class Map {
     
    	private int finishx, finishy;
    	private boolean found = false;
    	private Scanner mazeFile;
    	private char[][] maze;
     
    	private void loadMap(){
    		maze = new char[Integer.parseInt(mazeFile.nextLine())][Integer.parseInt(mazeFile.nextLine())];
    		for(int i = 0; i < maze.length; i++)
    			maze[i] = mazeFile.nextLine().toCharArray();
    	}
     
    	private void traverseMap(int y, int x, char Finish){
    		if(maze[y][x] != '#'){
    			finishx = finishy = -1;
    			return;
    		}
    		if(x != 0){
    			if(maze[y][x-1] == '#' || maze[y][x-1] == '$'){
    				if(maze[y][x-1] == '$'){
    					finishy = y;
    					finishx = x-1;
    					found = true;
    					maze[y][x] = '%';
    					return;
    				}else{
    					maze[y][x] = '%';
    					traverseMap(y, x-1, Finish);
    				}
    			}
    		}
    		if(found) return;
     
    		if(y != 0){
    			if(maze[y-1][x] == '#' || maze[y-1][x] == '$'){
    				if(maze[y-1][x] == '$'){
    					finishy = y-1;
    					finishx = x;
    					found = true;
    					maze[y][x] = '%';
    					return;
    				}else{
    					maze[y][x] = '%';
    					traverseMap(y-1, x, Finish);
    				}
    			}
    		}
    		if(found) return;
     
    		if(x != maze.length-1){
    			if(maze[y][x+1] == '#' || maze[y][x+1] == '$'){
    				if(maze[y][x+1] == '$'){
    					finishy = y;
    					finishx = x+1;
    					found = true;
    					maze[y][x] = '%';
    					return;
    				}else{
    					maze[y][x] = '%';
    					traverseMap(y, x+1, Finish);
    				}
    			}
    		}
    		if(found) return;
     
    		if(y != maze[0].length-1){
    			if(maze[y+1][x] == '#' || maze[y+1][x] == '$'){
    				if(maze[y+1][x] == '$'){
    					finishy = y+1;
    					finishx = x;
    					found = true;
    					maze[y][x] = '%';
    					return;
    				}else{
    					maze[y][x] = '%';
    					traverseMap(y+1, x, Finish);
    				}
    			}
    		}
    		if(found) return;
    	}
     
    	public Map(String File){
    		try{
    			mazeFile = new Scanner(new FileReader(File));
    		}catch(FileNotFoundException fnfe){ System.err.println(fnfe.getMessage()); }
     
    		loadMap();
    		traverseMap(1, 1, '$');
     
    		System.out.println("Value at maze["+finishy+"]["+finishx+"]: "+maze[finishy][finishx]);
    	}
     
    	public static void main(String[] args) {
    		new Map("Maze.txt");
    	}
    }
    Regards,
    Chris
    Last edited by Freaky Chris; April 29th, 2009 at 04:38 AM. Reason: change "regards" to "Regards"

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