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POError when using backtracking recursive algorithm to generate maze
 

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  1. POError when using backtracking recursive algorithm to generate maze
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    <p>I am creating a maze generator using the recursive backtracking algorithm. However, my problem is that every time I run the program it gives the following result:</p> <pre><code>1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 0 0 0 0 0 0 0 1 1 1 0 0 0 0 0 0 1 1 1 1 0 0 0 0 0 1 1 1 1 1 0 0 0 0 1 1 1 1 1 1 0 0 0 1 1 1 1 1 1 1 0 0 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 0 1 1 1 1 1 1 1 1 1 </code></pre> <p>A little background on my code: The constructor fills the maze int array with 0s, and puts a 1 at the end position (0, 0), and then calls the backtrackGenerateMaze() method to randomly generate a maze. I think the problem may be that I don't have sort of walls, which may be making weird things happen. Also, for the directions: 0 = up, 1 = right, 2 = down, &amp; 3 = left. Hope that helps.</p> <p>Here's my code (sorry its so long, I've been trying to use comments to debug it):</p> <pre><code>public class Maze { private int width, length; private int[][] maze; public Maze(int rows, int columns) { width = columns; length = rows; maze = new int[rows][columns]; for (int i = 0; i &lt; rows; i++) { for (int j = 0; j &lt; columns; j++) { maze[i][j] = 0; } } maze[0][0] = 1; backtrackGenerateMaze(rows - 1, columns - 1, 1); } /* * THE PROBLEM MUST BE HERE IN THE backtrackGenerateMaze() METHOD */ private void backtrackGenerateMaze(int rows, int columns, int moveLength) { if (rows == 0 &amp;&amp; columns == 0) { System.out.println("rows = " + rows); System.out.println("length = " + length); System.out.println("columns = " + columns); System.out.println("width = " + width); return; } int[] randDirs = generateRandomDirections(); for (int dir : randDirs) { System.out.println("dir == " + dir); System.out.println("rows == " + rows); System.out.println("columns == " + columns + "\n"); if (dir == 0) { System.out.println("rows - moveLength == " + (rows - moveLength)); System.out.println("valid(rows - moveLength, columns) == " + (valid(rows - moveLength, columns))); System.out.println("isInRange(0, length, rows - moveLength, false) == " + (isInRange(0, length, rows - moveLength, false))); if (valid(rows - moveLength, columns) &amp;&amp; isInRange(0, length, rows - moveLength, false) &amp;&amp; maze[rows - moveLength][columns] != 1) { System.out.println("IF 0 is TRUE"); for (int i = 1; i &lt;= moveLength; i++) { maze[rows - moveLength][columns] = 1; } maze[rows][columns] = 1; System.out.println("HERE 0"); backtrackGenerateMaze(rows - moveLength, columns, moveLength); } // System.out.println("RETURN DIR 0"); // return; } else if (dir == 1) { System.out.println("columns + moveLength = " + (columns + moveLength)); System.out.println("valid(rows, columns + moveLength) = " + (valid(rows, columns + moveLength))); System.out.println(); if (valid(rows, columns + moveLength)) { System.out.println("VALID 1 is TRUE"); if (isInRange(0, width, columns + moveLength, false)) { System.out.println("isInRange() 1 is TRUE"); if (maze[rows][columns + moveLength] != 1) { System.out.println("square != 1 is TRUE"); System.out.println("IF 1 is TRUE"); for (int i = 1; i &lt;= moveLength; i++) { maze[rows][columns + moveLength] = 1; } maze[rows][columns] = 1; System.out.println("HERE 1"); backtrackGenerateMaze(rows, columns + moveLength, moveLength); } } } System.out.println("RETURN DIR 1"); return; } else if (dir == 2) { if (valid(rows + moveLength, columns) &amp;&amp; isInRange(0, length, rows + moveLength, false) &amp;&amp; maze[rows + moveLength][columns] != 1) { System.out.println("IF 2 is TRUE"); for (int i = 1; i &lt;= moveLength; i++) { maze[rows + moveLength][columns] = 1; } maze[rows][columns] = 1; System.out.println("HERE 2"); backtrackGenerateMaze(rows + moveLength, columns, moveLength); } System.out.println("RETURN DIR 2"); return; } else if (dir == 3) { if (valid(rows, columns - moveLength) &amp;&amp; isInRange(0, width, columns - moveLength, false) &amp;&amp; maze[rows][columns - moveLength] != 1) { System.out.println("IF 3 is TRUE"); for (int i = 1; i &lt;= moveLength; i++) { maze[rows][columns - moveLength] = 1; } maze[rows][columns] = 1; System.out.println("HERE 3"); backtrackGenerateMaze(rows + moveLength, columns - moveLength, moveLength); } System.out.println("RETURN DIR 3"); return; } } System.out.println("--------------------"); } public int[] generateRandomDirections() { ArrayList&lt;Integer&gt; rands = new ArrayList&lt;&gt;(); for (int i = 0; i &lt; 4; i++) { rands.add(i); } Collections.shuffle(rands); int[] ret = new int[4]; for (int i = 0; i &lt; rands.size(); i++) { ret[i] = rands.get(i); } return ret; } private boolean valid(int row, int column) { return isInRange(0, maze.length - 1, row, true) &amp;&amp; isInRange(0, maze[0].length - 1, column, true); } private boolean isInRange(int start, int end, int toCheck, boolean inclusive) { if (inclusive) { return (toCheck &gt;= start &amp;&amp; toCheck &lt;= end); } return (toCheck &gt; start &amp;&amp; toCheck &lt; end); } @Override public String toString() { String ret = ""; for (int i = 0; i &lt; maze.length; i++) { for (int j = 0; j &lt; maze[0].length; j++) { ret += maze[i][j] + " "; } ret += "\n"; } return ret; } } </code></pre> <p>...and here's the Main method I use to run it:</p> <pre><code>public class MazeGame { private static ArrayList&lt;Maze&gt; mazes = new ArrayList&lt;&gt;(); private static final int MAZE_SIZE = 10, NUM_MAZES = 1; public static void main(String[] args) { Maze temp; for (int i = 0; i &lt; NUM_MAZES; i++) { temp = new Maze(MAZE_SIZE, MAZE_SIZE); System.out.println(temp); mazes.add(temp); } } } </code></pre> <p>Any help is much appreciated.</p>
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    1. PTQuestion
    1. USiphonedev7
    1. USiphonedev7
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    1. This table or related slice is empty.
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    1. PO
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      1. POError when using backtracking recursive algorithm to generate maze
      1. This table or related slice is empty.
      1. VTDownMod
    1. COTry to build a [Short, Self Containd, Correct Example](http://sscce.org/)
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      1. POError when using backtracking recursive algorithm to generate maze
      1. USAubin
    2. COI would if I knew where the problem was...but there's so much code it's hard to trace (especially with the random part).
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      1. POError when using backtracking recursive algorithm to generate maze
      1. USiphonedev7
    3. COSure, but it's even harder for us! You have it all set up in your IDE ready to go. I'm afraid you will have to attack this with the debugger first.
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      1. POError when using backtracking recursive algorithm to generate maze
      1. USOliver Charlesworth
 

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