Java分别利用深度优先和广度优先求解迷宫路径

目录

• 深度优先
• 实现效果
• 示例代码
• 广度优先
• 实现效果
• 示例代码
• 知识点总结

深度优先

实现效果

示例代码

import java.awt.*;
import javax.swing.*;

public class AlgoFrame extends JFrame{

    private int canvasWidth;
    private int canvasHeight;

    public AlgoFrame(String title, int canvasWidth, int canvasHeight){

        super(title);

        this.canvasWidth = canvasWidth;
        this.canvasHeight = canvasHeight;

        AlgoCanvas canvas = new AlgoCanvas();
        setContentPane(canvas);
        pack();

        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setResizable(false);

        setVisible(true);
    }

    public AlgoFrame(String title){

        this(title, 1024, 768);
    }

    public int getCanvasWidth(){return canvasWidth;}
    public int getCanvasHeight(){return canvasHeight;}

    // data
    private MazeData data;
    public void render(MazeData data){
        this.data = data;
        repaint();
    }

    private class AlgoCanvas extends JPanel{

        public AlgoCanvas(){
            // 双缓存
            super(true);
        }

        @Override
        public void paintComponent(Graphics g) {
            super.paintComponent(g);

            Graphics2D g2d = (Graphics2D)g;

            // 抗锯齿
//            RenderingHints hints = new RenderingHints(
//                    RenderingHints.KEY_ANTIALIASING,
//                    RenderingHints.VALUE_ANTIALIAS_ON);
//            hints.put(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);
//            g2d.addRenderingHints(hints);

            // 具体绘制
            int w = canvasWidth/data.M();
            int h = canvasHeight/data.N();

            for(int i = 0 ; i < data.N() ; i ++ )
            {
                for(int j = 0 ; j < data.M() ; j ++){
                    if (data.getMaze(i, j) == MazeData.WALL)
                        AlgoVisHelper.setColor(g2d, AlgoVisHelper.LightBlue);
                    else
                        AlgoVisHelper.setColor(g2d, AlgoVisHelper.White);

                    if(data.path[i][j])
                    	AlgoVisHelper.setColor(g2d, AlgoVisHelper.Orange);

                    if(data.result[i][j])
                    	AlgoVisHelper.setColor(g2d, AlgoVisHelper.Red);

                    AlgoVisHelper.fillRectangle(g2d, j * w, i * h, w, h);
                }
            }

        }

        @Override
        public Dimension getPreferredSize(){
            return new Dimension(canvasWidth, canvasHeight);
        }
    }
}

import java.awt.*;
import java.awt.geom.Ellipse2D;

import java.awt.geom.Rectangle2D;
import java.lang.InterruptedException;

public class AlgoVisHelper {

    private AlgoVisHelper(){}

    public static final Color Red = new Color(0xF44336);
    public static final Color Pink = new Color(0xE91E63);
    public static final Color Purple = new Color(0x9C27B0);
    public static final Color DeepPurple = new Color(0x673AB7);
    public static final Color Indigo = new Color(0x3F51B5);
    public static final Color Blue = new Color(0x2196F3);
    public static final Color LightBlue = new Color(0x03A9F4);
    public static final Color Cyan = new Color(0x00BCD4);
    public static final Color Teal = new Color(0x009688);
    public static final Color Green = new Color(0x4CAF50);
    public static final Color LightGreen = new Color(0x8BC34A);
    public static final Color Lime = new Color(0xCDDC39);
    public static final Color Yellow = new Color(0xFFEB3B);
    public static final Color Amber = new Color(0xFFC107);
    public static final Color Orange = new Color(0xFF9800);
    public static final Color DeepOrange = new Color(0xFF5722);
    public static final Color Brown = new Color(0x795548);
    public static final Color Grey = new Color(0x9E9E9E);
    public static final Color BlueGrey = new Color(0x607D8B);
    public static final Color Black = new Color(0x000000);
    public static final Color White = new Color(0xFFFFFF);

    public static void strokeCircle(Graphics2D g, int x, int y, int r){

        Ellipse2D circle = new Ellipse2D.Double(x-r, y-r, 2*r, 2*r);
        g.draw(circle);
    }

    public static void fillCircle(Graphics2D g, int x, int y, int r){

        Ellipse2D circle = new Ellipse2D.Double(x-r, y-r, 2*r, 2*r);
        g.fill(circle);
    }

    public static void strokeRectangle(Graphics2D g, int x, int y, int w, int h){

        Rectangle2D rectangle = new Rectangle2D.Double(x, y, w, h);
        g.draw(rectangle);
    }

    public static void fillRectangle(Graphics2D g, int x, int y, int w, int h){

        Rectangle2D rectangle = new Rectangle2D.Double(x, y, w, h);
        g.fill(rectangle);
    }

    public static void setColor(Graphics2D g, Color color){
        g.setColor(color);
    }

    public static void setStrokeWidth(Graphics2D g, int w){
        int strokeWidth = w;
        g.setStroke(new BasicStroke(strokeWidth, BasicStroke.CAP_ROUND, BasicStroke.JOIN_ROUND));
    }

    public static void pause(int t) {
        try {
            Thread.sleep(t);
//            System.out.println("Dely");
        }
        catch (InterruptedException e) {
            System.out.println("Error sleeping");
        }
    }

}

import java.awt.*;
import java.util.Stack;

public class AlgoVisualizer {

    private static int DELAY = 10;
    private static int blockSide = 8;

    private MazeData data;
    private AlgoFrame frame;

    private static final int d[][] = {{-1,0}, {0, 1}, {1, 0}, {0, -1}};  //左下右上

    public AlgoVisualizer(String mazeFile){

        // 初始化数据
        data = new MazeData(mazeFile);
        int sceneHeight = data.N() * blockSide;
        int sceneWidth = data.M() * blockSide;

        // 初始化视图
        EventQueue.invokeLater(() -> {
            frame = new AlgoFrame("Maze Solver Visualization", sceneWidth, sceneHeight);

            new Thread(() -> {
                run();
            }).start();
        });
    }

    public void run(){

        setData(-1, -1, false);

        Stack<Position> stack = new Stack<Position>();
        Position entrance = new Position(data.getEntranceX(), data.getEntranceY());
        stack.push(entrance);
        data.visited[entrance.getX()][entrance.getY()] = true;

        boolean isSolved = false;
        while (!stack.empty()) {
        	Position curPos = stack.pop();
        	setData(curPos.getX(), curPos.getY(), true);

        	if (curPos.getX() == data.getExitX() && curPos.getY() == data.getExitY()) {
        		isSolved = true;
        		findPath(curPos);  //find the path from the final position
        		break;
        	}

        	for (int i = 0; i < 4; i++) {
        		int newX = curPos.getX() + d[i][0];
        		int newY = curPos.getY() + d[i][1];

        		if (data.inArea(newX, newY) && !data.visited[newX][newY] &&
        				data.getMaze(newX, newY) == MazeData.ROAD) {
        			stack.push(new Position(newX, newY, curPos));
        			data.visited[newX][newY] = true;
				}
			}

		}

        if (!isSolved) {
			System.out.println("the maze has no solution");
		}
        setData(-1, -1, false);
    }

    public void findPath(Position des) {
    	Position cur = des;
    	while (cur != null) {
    		data.result[cur.getX()][cur.getY()] = true;
			cur = cur.getPrev();
		}

	}

    private void setData(int x, int y, boolean isPath){
    	if (data.inArea(x, y)) {
    		data.path[x][y] = isPath;
		}

        frame.render(data);
        AlgoVisHelper.pause(DELAY);
    }

    public static void main(String[] args) {

        String mazeFile = "maze_101_101.txt";

        AlgoVisualizer vis = new AlgoVisualizer(mazeFile);

    }
}

import java.io.BufferedInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.util.Scanner;

public class MazeData {

    public static final char ROAD = ' ';
    public static final char WALL = '#';

    private int N, M;
    private char[][] maze;

    private int entranceX, entranceY;
    private int exitX, exitY;

    public boolean[][] visited;
    public boolean[][] path;
    public boolean[][] result;

     public MazeData(String filename){

        if(filename == null)
            throw new IllegalArgumentException("Filename can not be null!");

        Scanner scanner = null;
        try{
            File file = new File(filename);
            if(!file.exists())
                throw new IllegalArgumentException("File " + filename + " doesn't exist");

            FileInputStream fis = new FileInputStream(file);
            scanner = new Scanner(new BufferedInputStream(fis), "UTF-8");

            // 读取第一行
            String nmline = scanner.nextLine();
            String[] nm = nmline.trim().split("\\s+");
            //System.out.print(nm[0] + ' ' + nm[1]);

            N = Integer.parseInt(nm[0]);
            // System.out.println("N = " + N);
            M = Integer.parseInt(nm[1]);
            // System.out.println("M = " + M);

            // 读取后续的N行
            maze = new char[N][M];
            visited = new boolean[N][M];
            path = new boolean[N][M];
            result = new boolean[N][M];

            for(int i = 0 ; i < N ; i ++){
                String line = scanner.nextLine();

                // 每行保证有M个字符
                if(line.length() != M)
                    throw new IllegalArgumentException("Maze file " + filename + " is invalid");
                for(int j = 0 ; j < M ; j ++)
                {
                    maze[i][j] = line.charAt(j);
                    visited[i][j] = false;
                    path[i][j] = false;
                    result[i][j] = false;

                }
            }
        }
        catch(IOException e){
            e.printStackTrace();
        }
        finally {
            if(scanner != null)
                scanner.close();
        }

        entranceX = 1;
        entranceY = 0;
        exitX = N - 2 ;
        exitY = M - 1;
    }

    public int N(){ return N; }
    public int M(){ return M; }
    public int  getEntranceX() {return entranceX;}
    public int  getEntranceY() {return entranceY;}
    public int getExitX() { return exitX;}
    public int getExitY() { return exitY;}

    public char getMaze(int i, int j){
        if(!inArea(i,j))
            throw new IllegalArgumentException("i or j is out of index in getMaze!");

        return maze[i][j];
    }

    public boolean inArea(int x, int y){
        return x >= 0 && x < N && y >= 0 && y < M;
    }

    public void print(){
        System.out.println(N + " " + M);
        for(int i = 0 ; i < N ; i ++){
            for(int j = 0 ; j < M ; j ++)
                System.out.print(maze[i][j]);
            System.out.println();
        }
        return;
    }

}

public class Position {

	private int x, y;
	private Position prev;

	public Position(int x, int y, Position prev ) {
		// TODO Auto-generated constructor stub
		this.x = x;
		this.y = y;
		this.prev = prev;
	}

	public Position(int x, int y) {
		// TODO Auto-generated constructor stub
		this(x, y, null);
	}

	public int getX() { return x;}
	public int getY() { return y;}
	public Position getPrev() {return prev;}

}

上面是深度优先的非递归遍历方法

下面是广度优先的遍历方法

广度优先

实现效果

示例代码

import java.awt.*;
import java.util.LinkedList;
import java.util.Stack;

public class AlgoVisualizer {

    private static int DELAY = 10;
    private static int blockSide = 8;

    private MazeData data;
    private AlgoFrame frame;

    private static final int d[][] = {{-1,0}, {0, 1}, {1, 0}, {0, -1}};  //左下右上

    public AlgoVisualizer(String mazeFile){

        // 初始化数据
        data = new MazeData(mazeFile);
        int sceneHeight = data.N() * blockSide;
        int sceneWidth = data.M() * blockSide;

        // 初始化视图
        EventQueue.invokeLater(() -> {
            frame = new AlgoFrame("Maze Solver Visualization", sceneWidth, sceneHeight);

            new Thread(() -> {
                run();
            }).start();
        });
    }

    public void run(){

        setData(-1, -1, false);

        LinkedList<Position> queue = new LinkedList<Position>();
        Position entrance = new Position(data.getEntranceX(), data.getEntranceY());
        queue.addLast(entrance);
        data.visited[entrance.getX()][entrance.getY()] = true;

        boolean isSolved = false;
        while ( queue.size() != 0) {
        	Position curPos = queue.pop();
        	setData(curPos.getX(), curPos.getY(), true);

        	if (curPos.getX() == data.getExitX() && curPos.getY() == data.getExitY()) {
        		isSolved = true;
        		findPath(curPos);  //find the path from the final position
        		break;
        	}

        	for (int i = 0; i < 4; i++) {
        		int newX = curPos.getX() + d[i][0];
        		int newY = curPos.getY() + d[i][1];

        		if (data.inArea(newX, newY) && !data.visited[newX][newY] &&
        				data.getMaze(newX, newY) == MazeData.ROAD) {
        			queue.addLast(new Position(newX, newY, curPos));
        			data.visited[newX][newY] = true;
				}
			}

		}

        if (!isSolved) {
			System.out.println("the maze has no solution");
		}
        setData(-1, -1, false);
    }

    public void findPath(Position des) {
    	Position cur = des;
    	while (cur != null) {
    		data.result[cur.getX()][cur.getY()] = true;
			cur = cur.getPrev();
		}

	}

    private void setData(int x, int y, boolean isPath){
    	if (data.inArea(x, y)) {
    		data.path[x][y] = isPath;
		}

        frame.render(data);
        AlgoVisHelper.pause(DELAY);
    }

    public static void main(String[] args) {

        String mazeFile = "maze_101_101.txt";

        AlgoVisualizer vis = new AlgoVisualizer(mazeFile);

    }
}

知识点总结

q为抽象的队列

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