Task: Munching squares
C++: #include <windows.h>
#include <string>


using namespace std;


const int BMP_SIZE = 512;


class myBitmap
{
public:
    myBitmap() : pen( NULL ), brush( NULL ), clr( 0 ), wid( 1 ) {}
    ~myBitmap()
    {
	DeleteObject( pen );
	DeleteObject( brush );
	DeleteDC( hdc );
	DeleteObject( bmp );
    }
 
    bool create( int w, int h )
    {
	BITMAPINFO    bi;
	ZeroMemory( &bi, sizeof( bi ) );
	bi.bmiHeader.biSize        = sizeof( bi.bmiHeader );
	bi.bmiHeader.biBitCount    = sizeof( DWORD ) * 8;
	bi.bmiHeader.biCompression = BI_RGB;
	bi.bmiHeader.biPlanes      = 1;
	bi.bmiHeader.biWidth       =  w;
	bi.bmiHeader.biHeight      = -h;
 
	HDC dc = GetDC( GetConsoleWindow() );
	bmp = CreateDIBSection( dc, &bi, DIB_RGB_COLORS, &pBits, NULL, 0 );
	if( !bmp ) return false;
 
	hdc = CreateCompatibleDC( dc );
	SelectObject( hdc, bmp );
	ReleaseDC( GetConsoleWindow(), dc );
 
	width = w; height = h;
	return true;
    }
 
    void clear( BYTE clr = 0 )
    {
	memset( pBits, clr, width * height * sizeof( DWORD ) );
    }
 
    void setBrushColor( DWORD bClr )
    {
	if( brush ) DeleteObject( brush );
	brush = CreateSolidBrush( bClr );
	SelectObject( hdc, brush );
    }
 
    void setPenColor( DWORD c ) { clr = c; createPen(); }
 
    void setPenWidth( int w )   { wid = w; createPen(); }
 
    void saveBitmap( string path )
    {
	BITMAPFILEHEADER fileheader;
	BITMAPINFO       infoheader;
	BITMAP           bitmap;
	DWORD            wb;
 
	GetObject( bmp, sizeof( bitmap ), &bitmap );
	DWORD* dwpBits = new DWORD[bitmap.bmWidth * bitmap.bmHeight];
 
	ZeroMemory( dwpBits, bitmap.bmWidth * bitmap.bmHeight * sizeof( DWORD ) );
	ZeroMemory( &infoheader, sizeof( BITMAPINFO ) );
	ZeroMemory( &fileheader, sizeof( BITMAPFILEHEADER ) );
 
	infoheader.bmiHeader.biBitCount = sizeof( DWORD ) * 8;
	infoheader.bmiHeader.biCompression = BI_RGB;
	infoheader.bmiHeader.biPlanes = 1;
	infoheader.bmiHeader.biSize = sizeof( infoheader.bmiHeader );
	infoheader.bmiHeader.biHeight = bitmap.bmHeight;
	infoheader.bmiHeader.biWidth = bitmap.bmWidth;
	infoheader.bmiHeader.biSizeImage = bitmap.bmWidth * bitmap.bmHeight * sizeof( DWORD );
 
	fileheader.bfType    = 0x4D42;
	fileheader.bfOffBits = sizeof( infoheader.bmiHeader ) + sizeof( BITMAPFILEHEADER );
	fileheader.bfSize    = fileheader.bfOffBits + infoheader.bmiHeader.biSizeImage;
 
	GetDIBits( hdc, bmp, 0, height, ( LPVOID )dwpBits, &infoheader, DIB_RGB_COLORS );
 
	HANDLE file = CreateFile( path.c_str(), GENERIC_WRITE, 0, NULL, CREATE_ALWAYS, FILE_ATTRIBUTE_NORMAL, NULL );
	WriteFile( file, &fileheader, sizeof( BITMAPFILEHEADER ), &wb, NULL );
	WriteFile( file, &infoheader.bmiHeader, sizeof( infoheader.bmiHeader ), &wb, NULL );
	WriteFile( file, dwpBits, bitmap.bmWidth * bitmap.bmHeight * 4, &wb, NULL );
	CloseHandle( file );
 
	delete [] dwpBits;
    }
 
    HDC getDC() const     { return hdc; }
    int getWidth() const  { return width; }
    int getHeight() const { return height; }
 
private:
    void createPen()
    {
	if( pen ) DeleteObject( pen );
	pen = CreatePen( PS_SOLID, wid, clr );
	SelectObject( hdc, pen );
    }
 
    HBITMAP bmp;
    HDC     hdc;
    HPEN    pen;
    HBRUSH  brush;
    void    *pBits;
    int     width, height, wid;
    DWORD   clr;
};

class mSquares
{
public:
    mSquares()
    {
        bmp.create( BMP_SIZE, BMP_SIZE );
        createPallete();
    }

    void draw()
    {
	HDC dc = bmp.getDC();
	for( int y = 0; y < BMP_SIZE; y++ )
	    for( int x = 0; x < BMP_SIZE; x++ )
	    {
		int c = ( x ^ y ) % 256;
		SetPixel( dc, x, y, clrs[c] );
	    }

	BitBlt( GetDC( GetConsoleWindow() ), 30, 30, BMP_SIZE, BMP_SIZE, dc, 0, 0, SRCCOPY );
	
    }

private:
    void createPallete()
    {
	for( int x = 0; x < 256; x++ )
	clrs[x] = RGB( x<<1, x, x<<2 );
    }

    unsigned int clrs[256];
    myBitmap bmp;
};

int main( int argc, char* argv[] )
{
    ShowWindow( GetConsoleWindow(), SW_MAXIMIZE );
    srand( GetTickCount() );
    mSquares s; s.draw();
    return system( "pause" );
}


Java: import java.awt.Color;
import java.awt.Graphics;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class XorPattern extends JFrame{
    private JPanel xorPanel;

    public XorPattern(){
        xorPanel = new JPanel(){
            @Override
            public void paint(Graphics g) {
                for(int y = 0; y < getHeight();y++){
                    for(int x = 0; x < getWidth();x++){
                        g.setColor(new Color(0, (x ^ y) % 256, 0));
                        g.drawLine(x, y, x, y);
                    }
                }
            }
        };
        add(xorPanel);
        setSize(300, 300);
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setVisible(true);
    }

    public static void main(String[] args){
        new XorPattern();
    }
}