nqueen.java

N-Queen solver written in java with excellent Graphical user interface.

/*
 * nqueen.java
 *
 * Created on January 21, 2008, 12:50 PM
 *
 * To change this template, choose Tools | Template Manager
 * and open the template in the editor.
 */

/**
 *
 * @author Gopal Lal and Sandeepan Jindal
 */
 
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;

public class nqueen extends JApplet implements ActionListener{
	String po = JOptionPane.showInputDialog(this,"Dimension of The Board");
	int poo = Integer.parseInt(po);
	int BOARD_SIZE = poo;
    private final static int WINDOW_WIDTH = 800;
    private final static int WINDOW_HEIGHT = 700;
    final static int IDEL = 0;
    final static int CLEAR = 1;
    final static int STEEPEST_WITHOUT_RANDOM = 2;
    final static int STEEPEST_WITH_RANDOM = 3;
    final static int FIRST__WITHOUT_RANDOM = 4;
	final static int FIRST__WITH_RANDOM = 5;
    JButton clear = new JButton("Clear");
    JButton Steepest_Random = new JButton("Steepest & Random");
    JButton Steepest_Normal = new JButton("Steepest Normal");
    JButton FirstChoice_Random = new JButton("First Choice & Random");
	JButton FirstChoice_Normal = new JButton("First Choice Normal");
    JTextArea stepCounterTextArea = new JTextArea("0", 1, 10);
	JTextArea DeadEndTextArea = new JTextArea("0", 1, 10);
    MyBoard b = new MyBoard();

    //------------------------------------------------
    // Init the entrire JFrame.
    //------------------------------------------------
    public void init() {
        getContentPane().setLayout(new BorderLayout());
        getContentPane().add("Center", b);
        Panel textPanel = new Panel();
        textPanel.setLayout(new BorderLayout(4, 1));
        textPanel.add("North", new JLabel("  "));
        textPanel.add("West", new JLabel("  "));
        textPanel.add("East", new JLabel("  "));
        textPanel.add("South", new JLabel("  "));

        Panel textCenterPanel = new Panel();
        textCenterPanel.setLayout(new GridLayout(5, 1));
        textCenterPanel.add(new JLabel("Step Counter :"));
        textCenterPanel.add(stepCounterTextArea);
		textCenterPanel.add(new JLabel("  "));
        textCenterPanel.add(new JLabel("Dead End or complte solution :"));
        textCenterPanel.add(DeadEndTextArea);
        textPanel.add("Center", textCenterPanel);
        //textPanel.add("Center", textCenterPanel);

        getContentPane().add("East", textPanel);
       // Add the button Panel onto the south of the frame.
        Panel buttonPanel = new Panel();
        buttonPanel.setLayout(new GridLayout(2, 4));
        buttonPanel.add(new JLabel(" "));
        buttonPanel.add(new JLabel(" "));
        buttonPanel.add(new JLabel(" "));
        buttonPanel.add(new JLabel(" "));
		buttonPanel.add(new JLabel(" "));
        buttonPanel.add(clear);
        buttonPanel.add(Steepest_Random);
        buttonPanel.add(Steepest_Normal);
        buttonPanel.add(FirstChoice_Random);
		buttonPanel.add(FirstChoice_Normal);
        getContentPane().add("South", buttonPanel);

        clear.addActionListener(this);
        Steepest_Random.addActionListener(this);
        Steepest_Normal.addActionListener(this);
        FirstChoice_Random.addActionListener(this);
		FirstChoice_Normal.addActionListener(this);
    }

    //-------------------------------------------------------------
    // Listen to the actions of the buttons and the slider.
    //-------------------------------------------------------------
    public void actionPerformed(ActionEvent e) {
        if (e.getSource() == clear) 
		{
            b.initBoard();
            b.paint(b.getGraphics());
            stepCounterTextArea.setText("0");
			DeadEndTextArea.setText("");
            //soluCounterTextArea.setText("0");
        } 
		else if (e.getSource() == Steepest_Random) 
		{
            b.initBoard();
			b.paint(b.getGraphics());
			b.firstRandom(2);
			//b.steepestRandom();
        } 
		else if (e.getSource() == Steepest_Normal)
		{
            b.initBoard();
			b.paint(b.getGraphics());
			b.firstRandom(0);
            //b.steepestWithoutRandom();
		} 
		else if (e.getSource() == FirstChoice_Random) 
		{
            b.initBoard();
			b.paint(b.getGraphics());
            b.firstRandom(3);
        }
		else if (e.getSource() == FirstChoice_Normal) 
		{
            b.initBoard();
			b.paint(b.getGraphics());
			b.firstRandom(1);
            //b.firstWithoutRandom();
        }
    }


    public static void main(String[] args) {
        JFrame applicationFrame = new JFrame("NQueens Problem - cs433");

        // kill application when window closes
        applicationFrame.addWindowListener(new WindowAdapter() {
                public void windowClosing(WindowEvent e) {
                    System.exit(0);
                }
            });

        nqueen appletObject = new nqueen();
        appletObject.init();

        applicationFrame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
        applicationFrame.getContentPane().add(appletObject);
        applicationFrame.pack();

        applicationFrame.setSize(WINDOW_WIDTH, WINDOW_HEIGHT);
        applicationFrame.setVisible(true);
    }

    //----------------------------------------------------------------
    // Define the board and the operations on it.
    //----------------------------------------------------------------
    private class MyBoard extends Canvas  {
        final static int NO_QUEEN_AND_SAFE = 0;
        final static int QUEEN = 2;
        int status = IDEL;
        int stepCounter = 0;
        int soluCounter = 0;
        int delay = 0;
        int[][] grid = new int[BOARD_SIZE][BOARD_SIZE];
        MyBoard next;
        Graphics gr = this.getGraphics();
        int gWidth;
        int gHeight;

        // Constructor of the class of MyBoard
        //---------------------------------------------------------
        public MyBoard() {
                        initBoard();
        }

        // Reset the status of the board.
        //--------------------------------------------------------
        public void setStatus(int newStatus) {
            status = newStatus;
        }

        // Initializes the configuration of this board.
        //-----------------------------------------------------------
        public void initBoard() {
            for (int i = 0; i < BOARD_SIZE; i++)
                for (int j = 0; j < BOARD_SIZE; j++)
                    grid[i][j] = 0;
            next = null;
            stepCounter = 0;
            soluCounter = 0;
        }

          public void paint(Graphics g) 
		  {
            gr = g;
            gWidth = getBounds().width / BOARD_SIZE;
            gHeight = getBounds().height / BOARD_SIZE;

            for (int i = 0; i < BOARD_SIZE; i++)
                for (int j = 0; j < BOARD_SIZE; j++)
                    drawCell(i, j);
		  }

        // Draw a specific cell on the board.
        //---------------------------------------------------------
        private void drawCell(int x, int y)
		{
            int dark = 0;
            gr.setColor(Color.black);
            gr.drawRect(x * gWidth, y * gHeight, gWidth, gHeight);

            if (((x + y) % 2) == 0) 
			{
                dark = 20;
            }

            switch (grid[x][y]) 
			{
            case NO_QUEEN_AND_SAFE:
                gr.setColor(new Color(160 + dark, 110 + dark, 110 + dark));

                break;

              case QUEEN:
                gr.setColor(new Color(0, 0, 0));

                break;
            }

            gr.fillRect((x * gWidth) + 1, (y * gHeight) + 1, gWidth - 1,
                gHeight - 1);
        }

		public void firstRandom(int flag)
		{
		  MyBoard frand = new MyBoard();
		  MyBoard fRand = frand;
		  frand.initBoard();
		  stepCounter = 0;
		  NQueensBoard DV= new NQueensBoard(BOARD_SIZE);
		  DV.randomPlaceQueens();
		  stepCounter = DV.reduceConflict(flag);
		  boolean status = DV.isConflict();
		  stepCounterTextArea.setText(Integer.toString(stepCounter));
		  if(status == true)
		  {DeadEndTextArea.setText("TRY AGAIN,Press CLEAR");}
		  else{DeadEndTextArea.setText("Hurray!!! You got a solution");}
		  for (int i = 0; i < BOARD_SIZE; i++)
		  {
			  grid[i][DV.index[i]] =2;
		  paint(this.getGraphics());

		}
		
		}
}
 }