八数码 Java实现

参考http://blog.csdn.net/helloworld10086/article/details/41853389

package com.EightNumber.view;  
import java.util.*;  
  
public class EightNumPath {  
    final static int dx[] = {-1, 1, 0, 0};  
    final static int dy[] = { 0, 0,-1, 1};  
    final static String dir = "UDLR";  
    static int maxstate = 400000;  
    static int [][]st = new int[maxstate][9];  
    static int []goal = {1,2,3,4,5,6,7,8,0};  
    static int []dist = new int[maxstate];  
    static int []fa = new int[maxstate];  
    static int []move = new int[maxstate];  
    static boolean []vis = new boolean[maxstate];  
    static int []fact = new int[9];  
    static StringBuffer path;  
    public static boolean isok(int []a) {  
        int sum=0;  
        for(int i=0; i < 9; i++)    
            for(int j=i+1; j < 9; j++)    
                if(a[j] != 0 && a[i] != 0 && a[i] > a[j])    
                    sum++;  
        if(sum % 2 == 0) {  
            return true;  
        }  
        return false;  
    }    
    private static void init_lookup_table() {  
        fact[0] = 1;  
        for(int i = 1; i < 9; i++) {  
            fact[i] = fact[i-1] * i;  
        }  
        Arrays.fill(vis, false);  
    }  
    private static boolean try_to_insert(int s) {  
        int code = 0;  
        for(int i = 0; i < 9; i++) {  
            int cnt = 0;  
            for(int j = i+1; j < 9; j++) {  
                if(st[s][j] < st[s][i]) {  
                    cnt++;  
                }  
            }  
            code += fact[8-i] * cnt;  
        }  
        if(vis[code]) {  
            return false;  
        }  
        return vis[code] = true;  
    }  
      
    private static void print_path(int cur) {  
        while(cur != 1) {  
            path.insert(0,dir.charAt(move[cur]));  
            cur = fa[cur];  
        }  
    }  
    private static int bfs() {  
        init_lookup_table();  
        int front = 1 , rear = 2;  
        try_to_insert(front);  
        while(front < rear) {  
            if(Arrays.equals(st[front], goal)) {  
                return front;  
            }  
            int z;  
            for(z = 0; z < 9; z++) {  
                if(st[front][z] == 0) {  
                    break;  
                }  
            }  
            int x = z/3, y = z%3;  
            for(int d = 0; d < 4; d++) {  
                int newx = x + dx[d];  
                int newy = y + dy[d];  
                int newz = newx * 3 + newy;  
                if(newx >= 0 && newx < 3 && newy >= 0 && newy < 3) {  
                    st[rear] = Arrays.copyOf(st[front], st[front].length);  
                    st[rear][newz] = st[front][z];  
                    st[rear][z] = st[front][newz];  
                    dist[rear] = dist[front] + 1;  
                      
                    if(try_to_insert(rear)) {  
                        fa[rear] = front;  
                        move[rear] = d;  
                        rear++;  
                    }  
                }  
            }  
            front++;  
        }  
        return 0;  
    }  
    public static String solve(String state) {  
        path = new StringBuffer();  
        for(int i = 0; i < state.length(); i++) {  
            st[1][i] = Integer.valueOf(state.charAt(i)) - '0';  
        }  
        int ans = bfs();  
        print_path(ans);
        return path.toString();
    }  
}  

下面是主函数

package com.EightNumber.view;  
import java.awt.*;  
import javax.swing.*;  
import java.awt.event.*;  
import java.util.*;  
  
public class EightNumFrame extends Frame implements ActionListener,KeyListener  
{  
    MenuBar menubar=new MenuBar();  
    Menu menu_file = new Menu("文件(F)");  
    MenuItem restart = new MenuItem("重新开始");  
    MenuItem nextPath = new MenuItem("提示");  
    MenuItem printPath = new MenuItem("还原");  
    MenuItem exit = new MenuItem("退出");  
    Button[] button;  
    Panel panel;  
    int row,col;  
    private static int position,cellNum;  
    final int dr[] = { 0,-1, 0, 1};  
    final int dc[] = {-1, 0, 1, 0};  
    public EightNumFrame(int row,int col) {  
        super.setMenuBar(menubar);  
        //Windows风格   
        try {  
            UIManager.setLookAndFeel("com.sun.java.swing.plaf.windows.WindowsLookAndFeel");  
        } catch (Exception e) {  
            e.printStackTrace();  
        }  
        this.row = row;  
        this.col = col;  
        cellNum = row*col;  
          
        restart.addActionListener(this);  
        exit.addActionListener(this);  
        nextPath.addActionListener(this);  
        printPath.addActionListener(this);  
        menu_file.add(restart);  
        menu_file.add(nextPath);  
        menu_file.add(printPath);  
        menu_file.add(exit);  
        menubar.add(menu_file);  
          
        panel = new Panel(new GridLayout(row,col)) ;  
        button = new Button[cellNum];  
        for(int i = 0; i < cellNum; i++) {  
            if(i == cellNum - 1) {  
                button[i] = new Button(" ");  
            }else {  
                button[i] = new Button(String.valueOf(i + 1));  
            }  
            button[i].setFont(new Font("Courier", 1, 20));  
            button[i].addActionListener(this);  
            button[i].addKeyListener(this);  
            panel.add(button[i]);  
        }  
        position = cellNum - 1;  
        this.add(BorderLayout.CENTER,panel);  
        this.setTitle("八数码");  
        this.setVisible(true);  
        this.setSize(300,300);  
          
        Toolkit kit = Toolkit.getDefaultToolkit();  
        Dimension screenSize = kit.getScreenSize();  
        int screenWidth = screenSize.width/2;  
        int screenHeight = screenSize.height/2;  
        int height = this.getHeight();  
        int width = this.getWidth();  
        this.setLocation(screenWidth-width/2, screenHeight-height/2);  
        this.addWindowListener(new WindowAdapter() {  
            public void windowClosing(WindowEvent e) {  
                System.exit(0);  
            }  
        });  
    }  
    void start() {  
        int a[] = new int[9];  
        do {  
            int k = 0;  
            Random random=new Random();  
            Set<Integer> set=new HashSet<Integer>();  
            while(set.size() < cellNum-1) {  
                int n=random.nextInt(cellNum-1)+1;  
                if(!set.contains(n)) {  
                    set.add(n);  
                    a[k++] = n;  
                }  
            }  
            a[k] = 0;  
        }while(!EightNumPath.isok(a));  
        for(int i = 0; i < 9; i++)  
            button[i].setLabel(String.valueOf(a[i]));  
        button[cellNum-1].setLabel(" ");  
        position = cellNum - 1;  
    }  
    boolean win() {  
        for(int i = 0; i < cellNum - 1; i++) {  
            if(button[i].getLabel().equals(" ")) {  
                return false;  
            }else if(Integer.valueOf(button[i].getLabel()) != i+1) {  
                return false;  
            }  
        }  
        return true;  
    }  
    private boolean judge(Button a, Button b) {  
        for(int i = 0; i < 4; i++) {  
            if( (a.getX() == b.getX() + dr[i]*a.getWidth())   
                    && (a.getY() == b.getY() + dc[i]*a.getHeight())) {  
                return true;  
            }  
        }  
        return false;  
    }  
  
    public void actionPerformed(ActionEvent e) {  
        StringBuffer state = new StringBuffer();  
        if(e.getSource() == restart) {  
            start();  
            return;  
        }else if(e.getSource() == exit) {  
            System.exit(0);  
            return;  
        }else if(e.getSource() == nextPath) {  
            for(int i = 0; i < cellNum; i++) {  
                if(button[i].getLabel().equals(" ")) {  
                    state.append('0');  
                }else {  
                    state.append(button[i].getLabel());  
                }  
            }  
            String path = EightNumPath.solve(state.toString());  
            JOptionPane.showMessageDialog(this,"建议走："+path);  
            System.out.println(path);  
            return;  
        }else if(e.getSource() == printPath) {  
            for(int i = 0; i < cellNum; i++) {  
                if(button[i].getLabel().equals(" ")) {  
                    state.append('0');  
                }else {  
                    state.append(button[i].getLabel());  
                }  
            }  
            String path = EightNumPath.solve(state.toString());  
            for(int i = 0; i < path.length(); i++) {  
                switch(path.charAt(i)) {  
                case 'U':  
                    go(KeyEvent.VK_UP);  
                    break;  
                case 'D':  
                    go(KeyEvent.VK_DOWN);  
                    break;  
                case 'L':  
                    go(KeyEvent.VK_LEFT);  
                    break;  
                case 'R':  
                    go(KeyEvent.VK_RIGHT);  
                    break;  
                }  
                try {  
                    Thread.sleep(1000);  
                } catch (InterruptedException e1) {  
                    e1.printStackTrace();  
                }  
            }  
        }  
        for(int i = 0; i < cellNum; i++) {  
            if(e.getSource() == button[i]) {  
                if(!button[i].getLabel().equals(" ") && judge(button[i],button[position])) {  
                    button[position].setLabel(button[i].getLabel());  
                    button[i].setLabel(" ");  
                    position = i;  
                }  
            }  
        }  
        if(win()) {  
            JOptionPane.showMessageDialog(this,"Congratulations");  
        }  
    }  
    void go(int dir) {  
        int x = position / col;  
        int y = position % col;  
        switch(dir) {  
        case KeyEvent.VK_UP:  
            if(x != 0) {  
                button[position].setLabel(button[position-col].getLabel());  
                button[position-col].setLabel(" ");  
                position -= col;  
            }  
            break;  
        case KeyEvent.VK_DOWN:  
            if(x != row-1) {  
                button[position].setLabel(button[position+col].getLabel());  
                button[position+col].setLabel(" ");  
                position += col;  
            }  
            break;  
        case KeyEvent.VK_LEFT:  
            if(y != 0) {  
                button[position].setLabel(button[position-1].getLabel());  
                button[position-1].setLabel(" ");  
                position -= 1;  
            }  
            break;  
        case KeyEvent.VK_RIGHT:  
            if(y != col-1) {  
                button[position].setLabel(button[position+1].getLabel());  
                button[position+1].setLabel(" ");  
                position += 1;  
            }  
            break;  
        }  
    }  
    public void keyPressed(KeyEvent e) {  
        go(e.getKeyCode());  
        if(win()) {  
            JOptionPane.showMessageDialog(this,"Congratulations");  
        }  
    }  
    public void keyReleased(KeyEvent e) {}  
    public void keyTyped(KeyEvent e) {}  
    public static void main(String[] args) {  
        new EightNumFrame(3, 3);  
    }  
}