Arrays and Array Lists - Java Concepts - page 454

΢΢Exercise P7.13. Implement the following algorithm to construct magic
n-by-n 2 squares; it works only if n is odd. Place a 1 in the middle of the
bottom row. After k has been placed in the (i, j) square, place k+1 into the
square to the right and down , wrapping around the borders. However, if the
square to the right and down has already been filled, or if you are in the
lower-right corner, then you must move to the square straight up instead.
Here is the 5¶5 square that you get if you follow this method:

329
330

11 18 25 2 9

10 12 19 21 3

4 6 13 20 22

23 5 7 14 16

17 24 1 8 15

Write a program whose input is the number n and whose output is the
magic square of order n if n is odd. Implement a class MagicSquare
with a constructor that constructs the square and a toString method that
returns a representation of the square.

΢G Exercise P7.14. Implement a class Cloud that contains an array list of
Point 2D.Double objects. Support methods

public void add(Point2D.Double aPoint)
public void draw(Graphics2D g2)

Draw each point as a tiny circle.

Write a graphical application that draws a cloud of 100 random points.

΢΢G Exercise P7.15. Implement a class Polygon that contains an array list
of Point2D.Double objects. Support methods

public void add(Point2D.Double aPoint)
public void draw(Graphics2D g2)

Draw the polygon by joining adjacent points with a line, and then closing
it up by joining the end and start points.