绘制圆

在屏幕上用“*”画一个空心的圆

打印圆可利用图形的左右对称性。根据圆的方程：

R*R=X*X+Y*Y

可以算出圆上每一点行和列的对应关系。

-Draw a circle on the screen with " *"　to draw a hollow circle graph can be used to print the left and right circular symmetry. According to a circle equation: R* R = X* X+ Y* Y can be calculated at each point on the circle corresponding relationship between the rows and columns.