Java分別利用深度優先和廣度優先求解迷宮路徑
深度優先
實現效果
示例代碼
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(){ // 雙緩存 super(true); } @Override public void paintComponent(Graphics g) { super.paintComponent(g); Graphics2D g2d = (Graphics2D)g; // 抗鋸齒 // RenderingHints hints = new RenderingHints( // RenderingHints.KEY_ANTIALIASING, // RenderingHints.VALUE_ANTIALIAS_ON); // hints.put(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY); // g2d.addRenderingHints(hints); // 具體繪制 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){ // 初始化數據 data = new MazeData(mazeFile); int sceneHeight = data.N() * blockSide; int sceneWidth = data.M() * blockSide; // 初始化視圖 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"); // 讀取第一行 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); // 讀取後續的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(); // 每行保證有M個字符 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;} }
上面是深度優先的非遞歸遍歷方法
下面是廣度優先的遍歷方法
廣度優先
實現效果
示例代碼
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){ // 初始化數據 data = new MazeData(mazeFile); int sceneHeight = data.N() * blockSide; int sceneWidth = data.M() * blockSide; // 初始化視圖 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); } }
知識點總結
q為抽象的隊列
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