Friday, September 16, 2016
Simple NQueen Visualizer in JAVA to Visualize Backtracking
Information:
This is a simple NQueen GUI Problem solver coded in Java. It shows the rows and columns it is currently using and also shows the backtracking movements.The github repository for this code is,
https://github.com/quickgrid/NQueenVisualization/tree/masterVisualization 1:
Visualization 2:
Code:
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| /** | |
| * Author: Asif Ahmed | |
| * Site: https://quickgrid.wordpress.com | |
| * Description: N Queen visualizer Sample. | |
| */ | |
| import javax.swing.*; | |
| import java.awt.*; | |
| /** | |
| * Created by computer science on 12/6/2015. | |
| */ | |
| public class NQueen { | |
| final static int M = 10; | |
| static JLabel [][] jLabel = new JLabel[M][M]; | |
| static int board[][] = new int[M][M]; | |
| static void printSolution(){ | |
| for(int i = 0; i < M; ++i){ | |
| for(int j = 0; j < M; ++j){ | |
| System.out.printf("%d ", board[i][j]); | |
| } | |
| System.out.printf("\n"); | |
| } | |
| } | |
| static boolean isSafe( int row, int col ) { | |
| try { | |
| Thread.sleep(10); | |
| } catch (InterruptedException e) { | |
| e.printStackTrace(); | |
| } | |
| for (int i = 0; i < col; ++i) | |
| if (board[row][i] == 1) | |
| return false; | |
| for (int i = row, j = col; i >= 0 && j >= 0; --i, --j) { | |
| if (board[i][j] == 1) | |
| return false; | |
| } | |
| for (int i = row, j = col; i < M && j >= 0; ++i, --j){ | |
| if (board[i][j] == 1) | |
| return false; | |
| } | |
| return true; | |
| } | |
| static boolean findSolution( int col ){ | |
| if(col >= M) | |
| return true; | |
| for( int i = 0; i < M; ++i ){ | |
| //Increase the sleep value to slow down the animation | |
| try { | |
| Thread.sleep(0); | |
| } catch (InterruptedException e) { | |
| e.printStackTrace(); | |
| } | |
| if( isSafe( i, col) == true ){ | |
| board[i][col] = 1; | |
| jLabel[i][col].setBackground(Color.ORANGE); | |
| if( findSolution( col + 1) == true ) | |
| return true; | |
| board[i][col] = 0; | |
| jLabel[i][col].setBackground(Color.WHITE); | |
| //jLabel[i][col].setBackground(Color.BLUE); | |
| } | |
| } | |
| return false; | |
| } | |
| static void solveNQueen(){ | |
| try { | |
| Thread.sleep(500); | |
| } catch (InterruptedException e) { | |
| e.printStackTrace(); | |
| } | |
| // reset board | |
| for(int i = 0; i < M; ++i) { | |
| for (int j = 0; j < M; ++j) { | |
| try { | |
| Thread.sleep(10); | |
| } catch (InterruptedException e) { | |
| e.printStackTrace(); | |
| } | |
| board[i][j] = 0; | |
| jLabel[i][j].setBackground(Color.BLUE); | |
| } | |
| } | |
| //If solution exist print otherwise show error message | |
| if( findSolution( 0 ) == false ) | |
| System.out.println("No Solution.\n"); | |
| else | |
| printSolution(); | |
| } | |
| NQueen() { | |
| JFrame jFrame = new JFrame("NQueen Visualizer."); | |
| jFrame.setLayout(new GridLayout(M, M)); | |
| jFrame.setSize(500, 500); | |
| jFrame.setDefaultCloseOperation(jFrame.EXIT_ON_CLOSE); | |
| for(int i = 0; i < M; ++i) { | |
| for (int j = 0; j < M; ++j) { | |
| jLabel[i][j] = new JLabel( "(" + i + "," + j + ")" ); | |
| jLabel[i][j].setHorizontalAlignment(SwingConstants.CENTER); | |
| jLabel[i][j].setSize(50, 50); | |
| jLabel[i][j].setOpaque(true); | |
| //Random rand = new Random(); | |
| //jLabel[i].setBackground(new Color(rand.nextFloat(), rand.nextFloat(), rand.nextFloat())); | |
| jFrame.add(jLabel[i][j]); | |
| } | |
| } | |
| jFrame.setVisible(true); | |
| } | |
| public static void main( String args[] ){ | |
| SwingUtilities.invokeLater(new Runnable() { | |
| @Override | |
| public void run() { | |
| new NQueen(); | |
| } | |
| }); | |
| solveNQueen(); | |
| } | |
| } |
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