【发布时间】：2011-07-19 17:51:34
【问题描述】：
我寻求是否有人可以帮助我解决我的房间搜索算法
我正在尝试实现一个回溯算法来解决迷宫问题。我被困在我应该记住我已经访问过的房间的地方。
迷宫由房间组成，每个房间有 4 个面——北、东、南和西。每个房间都通过在所需一侧设置一扇门连接到下一个房间，即room1.createNorth(roomName)，它在北边创建了一个新房间，一个新房间有南门连接回第一个房间，正如您在我的 Room 课程中看到的那样。
这是我切碎的房间类，它代表迷宫中的每个房间。我删除了与我处理北侧的方法相同的南、西和东方向。
public class Room {
private String name;
private Room north;
private Room east;
private Room west;
private Room south;
private boolean isExit = false;
private Maze maze;
/**
* @return name room
*/
public String getName() {
return this.name;
}
/**
* Sets room name
*
* @param name
*/
public void setName(String name) {
this.name = name;
}
/**
* Gets northern room if any
*
* @return pointer to northern room if any, otherwise <code>null</code>
*/
public Room getNorth() {
return this.north;
}
/**
* Sets the door to the next room to the north in that room and in the other
* room sets southern door as connecting back to that room
*
* @param otherRoom
*/
public void setNorth(Room otherRoom) {
this.north = otherRoom;
otherRoom.south = this;
}
/**
* creates a new room to the north and connects back to this room
*
* @param name
* of the room
* @return created room
*/
public Room createNorth(String name) {
Room otherRoom = null;
// create new room in that direction ONLY if there is no room yet
if (this.getNorth() == null) { // get northern direction, if it's null,
// then it's okay to create there
otherRoom = new Room(); // create!
this.setNorth(otherRoom); // set the door
otherRoom.setName(name); // set the name
} else { // there is a room in that direction, so don't create a new
// room and drop a warning
System.out.println("There is already a room in northern direction");
}
return otherRoom;
}
/**
* Asdf
*
* @return maze
*/
public Maze getMaze() {
return this.maze;
}
/**
* Set maze
*
* @param maze
*/
public void setMaze(Maze maze) {
this.maze = maze;
}
/**
* @param roomName path to this room must be found
*/
public void findPathTo(String roomName) {
Room soughtRoom = this.getMaze().getEntry();
while (!(soughtRoom.getName().equalsIgnoreCase(roomName))) {
// here should be also a method such as setRoomAsVisited()
if (this.getWest() != null) {
soughtRoom = this.getWest();
this.getMaze().getPaths().push(soughtRoom);
}
else if (this.getNorth() != null) {
soughtRoom = this.getNorth();
this.getMaze().getPaths().push(soughtRoom);
}
else if (this.getEast() != null) {
soughtRoom = this.getEast();
this.getMaze().getPaths().push(soughtRoom);
}
else if (this.getSouth() != null) {
soughtRoom = this.getSouth();
this.getMaze().getPaths().push(soughtRoom);
}
else {
if (this.getMaze().getPaths().isEmpty()) {
break; // no more path for backtracking, exit (no solution found)
}
// dead end, go back!
soughtRoom = this.getMaze().getPaths().pop();
}
System.out.println(this.getMaze().getPaths().toString());
}
}
@Override
public String toString() {
return "Room name is " + this.getName();
}
}
迷宫看起来像这样：http://i.stack.imgur.com/2KePs.jpg 其中 S 是起点
我的迷宫课
public class Maze {
Room room;
/**
* helper collection path stack for findPathTo() method
*/
private Stack<Room> paths = new Stack<Room>();
/**
* @return path for exit
*/
public Stack<Room> getPaths() {
return this.paths;
}
/**
* Singleton method for first room in the maze which is entry room
*
* @return room if no room is created then creates new, otherwise returns
* already created room
*/
public Room getEntry() {
if (this.room == null) {
this.room = new Room();
return this.room;
}
return this.room;
}
}
这是我的主要课程 公共类主 {
public static void main(String[] args) {
Maze maze = new Maze();
maze.getEntry().setName("A4"); // set first room's name A4
// labyrinth creation
maze.getEntry().createEast("B4").createNorth("B3").createWest("A3");
maze.getEntry().getEast().getNorth().createNorth("B2").createWest("A2")
.createNorth("A1");
maze.getEntry().getEast().getNorth().getNorth().createNorth("B1");
maze.getEntry().getEast().getNorth().getNorth().createEast("C2")
.createNorth("C1").createEast("D1");
maze.getEntry().getEast().createEast("C4").createEast("D4");
maze.getEntry().getEast().getEast().createNorth("C3").createEast("D3")
.createNorth("D2").setExit(true);
System.out.println("=====Test findPathTo method======");
maze.getEntry().setMaze(maze); // set maze instance to our entrance room
maze.getEntry().findPathTo("B4");
System.out.println("=====End of testing findPathTo method======");
}
}
问题出在我的findPathTo(roomName) 方法中，它找到了通往房间的路线。
如果我进入房间 D4，那么我的算法只会从“A4”向东移动一次到“B4”房间，然后它会无限循环，堆栈只会随着房间“B4”而增长。为什么它不前进到下一个房间“B3”或“C4”？
编辑：这是工作代码
public void findPathTo(String roomName) {
Room soughtRoom = this.getMaze().getEntry();
while (!(soughtRoom.getName().equalsIgnoreCase(roomName))) {
if (soughtRoom.getWest() != null && soughtRoom.getWest().isVisited != true) {
this.getMaze().getPaths().push(soughtRoom);
soughtRoom = soughtRoom.getWest();
soughtRoom.isVisited = true;
}
else if (soughtRoom.getNorth() != null && soughtRoom.getNorth().isVisited != true) {
this.getMaze().getPaths().push(soughtRoom);
soughtRoom = soughtRoom.getNorth();
soughtRoom.isVisited = true;
}
else if (soughtRoom.getEast() != null && soughtRoom.getEast().isVisited != true) {
this.getMaze().getPaths().push(soughtRoom);
soughtRoom = soughtRoom.getEast();
soughtRoom.isVisited = true;
}
else if (soughtRoom.getSouth() != null && soughtRoom.getSouth().isVisited != true) {
this.getMaze().getPaths().push(soughtRoom);
soughtRoom = soughtRoom.getSouth();
soughtRoom.isVisited = true;
}
else {
if (this.getMaze().getPaths().isEmpty()) {
System.out.println("No solutions found :(");
break; // no more path for backtracking, exit (no solution found)
}
// dead end, go back!
soughtRoom = this.getMaze().getPaths().pop();
}
System.out.println("Path rooms: " + this.getMaze().getPaths().toString());
}
}
【问题讨论】：
-
添加一个“已访问”布尔标志，当您访问该房间时将其设置为 true。在回溯过程中，您只会通过尚未尝试过的房间。
-
嗨，谢谢。我做到了，这是最简单的方法。
标签： java algorithm maze backtracking