CS 111 - Program Design I

Spring 2015: Exam 2 Results and Solutions

Solutions:

1. a
2. b
3. b
4. d
5. c
6. d
7. c
8. a
9. b
10. a
11. c
12. b
13. a
14. d
15. a
16. d
17. b
18. c
19. b
20. c

public static Picture q21 ( Picture p ) 
  {
    
    int x;
    int y;
    
    //  loop for all of the columns in the picture
   
    for (  x = 0 ; x < p.getWidth() ; x++ )
    {
       // access column x in the picture
       for (  y = 0 ; y < p.getHeight() ;  y++ )
       {
         Pixel pix = p.getPixel(x, y);


         // manipulate pix as desired
         int r = pix.getRed();
         int g = pix.getGreen();
         int b = pix.getBlue();
         
         int grayAmount = (int)(r*0.299 + g*0.587 + b*0.114);
         
         if ( grayAmount < 85 )    // 255 / 3 is 85  ==> BLUE
         {
           pix.setColor (Color.BLUE);
         }
         else if ( grayAmount < 170 )   // 255 * 2 / 3 is 170  ==> GREEN
         {
           pix.setColor (Color.GREEN);
         }
         else                      // ==> CYAN
         {
           pix.setColor (Color.CYAN);
         } 
       }
    }
    
    return p;
  }
  

Question 22.

public static Picture q22 ( Picture p ) 
  {
    Picture result;
    
    int width = p.getWidth();
    int height = p.getHeight();
    
    result = new Picture ( width * 2, height );
    int x;
    int y;
    
    //  loop for all of the columns in the picture
   
    for (  x = 0 ; x < width ; x++ )
    {
       // access column x in the picture
       for (  y = 0 ; y < height ;  y++ )
       {
         Pixel pix = p.getPixel(x, y);
         Color c1 = pix.getColor();
         
         // copy the first pixel position
         int resultX = x;
         int resultY = y;
         
         Pixel resultPix = result.getPixel ( resultX, resultY );
         resultPix.setColor ( c1 );
         
         // copy into the second pixel position
         resultX = width + width-1 - x;
         resultY = y;
         
         resultPix = result.getPixel ( resultX, resultY );
         resultPix.setColor ( c1 );
       }
    }
    
    return result;
  }
  

-- Main.troy - 2015-04-24