Java 用递归解决迷宫问题

Question

我有一个任务，我应该能够显示从入口到导出的迷宫路径，我已经让它工作到一定程度，但是当迷宫变得更加复杂，有死胡同时，诸如程序进入无限递归。如果您能给我任何帮助，为我指明正确的方向，我们将不胜感激。

可以在 Room 类中找到 Mu 当前理论。

这里是 Room 类，其中存储了连接迷宫的每个房间的引用，有点像在 6 个方向(北、南、东、西、上、下)上链接的链表。

import java.util.ArrayList;

public class OurRoom
{
    private OurRoom exits[];
    private String name;
    private static ArrayList<OurRoom> list;

    public OurRoom()
    {
        this(null);
    }

    public OurRoom(String name)
    {
        this.name = name;
        this.list = new ArrayList<OurRoom>();
        exits = new OurRoom[Direction.values().length];
        for(OurRoom exit : exits)
        {
            exit = null;
        }
    }       


    public void connectTo(OurRoom theOtherRoom, Direction direction)
    {
        exits[direction.ordinal()] = theOtherRoom;
        theOtherRoom.exits[direction.getOpposite().ordinal()] = this;
    }

    public OurRoom getExit(Direction direction)
    {
        return exits[direction.ordinal()];
    }

    public boolean lookExit(Direction direction)
    {
        return exits[direction.ordinal()] != null;
    }

    public String getName() {
        return name;
    }

    public OurRoom solveRecursively(OurRoom exit) {
        list.add(this);
        if(this == exit) {
            return this;
        }else { 
            OurRoom temp = null;            
            if(lookExit(Direction.east)) {
                temp = exits[Direction.east.ordinal()].solveRecursively(exit);              
            }   
            else if(lookExit(Direction.up)) {
                temp = exits[Direction.up.ordinal()].solveRecursively(exit);
            }
            else if(lookExit(Direction.south)) {
                temp = exits[Direction.south.ordinal()].solveRecursively(exit);             
            }           
            else if(lookExit(Direction.down)) {
                temp = exits[Direction.down.ordinal()].solveRecursively(exit);
            }
            else if(lookExit(Direction.west)) {
                temp = exits[Direction.west.ordinal()].solveRecursively(exit);      
            }   
            else if(lookExit(Direction.north)) {
                temp = exits[Direction.north.ordinal()].solveRecursively(exit); 
            }
            return temp;
        }
    }

    public ArrayList<OurRoom> getList() {
        return list;
    }

}

这是方向枚举

public enum Direction
{
    north, south, east, west, up, down;

    public Direction getOpposite()
    {
        switch(this)
        {
            case north:
                return south;
            case south:
                return north;
            case east:
                return west;
            case west:
                return east;
            case up:
                return down;
            case down:
                return up;
            default:
                return this;
        }
    }
}

这是迷宫构建的示例。

import java.util.ArrayList;
import java.util.Iterator;

public class OurMaze
{
    private OurRoom entrance, exit;

    public OurMaze()
    {
        this(1);
    }

    public OurMaze(int mazeNumber)
    {
        entrance = null;
        exit = null;
        switch(mazeNumber)
        {
        case 0:
            break;
        case 1:
            this.buildMaze1();
            break;             
        default:
        }
    }

    public OurRoom getEntrance()
    {
        return entrance;
    }

    public OurRoom getExit()
    {
        return exit;
    }

    public Iterator<OurRoom> findPathRecursively() {
        entrance.solveRecursively(exit);
        ArrayList<OurRoom> list = entrance.getList();       
        return list.iterator();
    }

    private void buildMaze1()
    {
        OurRoom room1, room2;

        room1 = new OurRoom("Room 1");
        room2 = new OurRoom("Room 2");
        room1.connectTo(room2, Direction.north);

        entrance = room1;
        exit = room2;
    }

    public static void main(String[] args) {
        OurMaze maze = new OurMaze(1);      
    }
}

Answer 1

您只需要保留二维数组，其值指示单元格是否被访问:您不想两次访问同一个单元格。

除此之外，它只是广度优先搜索(如果您不想要最短路径，深度优先搜索也可以)。

一些链接
http://en.wikipedia.org/wiki/Flood_fill
http://en.wikipedia.org/wiki/Breadth-first_search
http://en.wikipedia.org/wiki/Depth-first_search

示例搜索例程。

    void dfs(int i, int j) {
        if cell(i, j) is outside of maze or blocked {
            return
        }
        if visited[i][j] {
            return
        }
        visited[i][j] = true;
        dfs(i + 1, j);
        dfs(i - 1, j);
        dfs(i, j + 1);
        dfs(i, j - 1);
    }

如果像 visited 一样，对于每个单元格，您都可以找到路径本身，您可以从中找到它。所以，打印看起来像这样(只是一个伪代码)。

var end = exit_point;
while (end != start_point) {
   print end;
   end = came_from[end];
}

编辑
上面的代码适用于二维迷宫，我刚刚注意到你有三维版本。但是在上面的例子中很容易引入第三个坐标。
如果有任何困难，请告诉我。