在屏幕上用“*”画一个空心的圆 *问题分析与算法设计：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。*思考题：实现函数y=x2的图形与圆的图形叠加显示.-On the screen with the "*" to draw a hollow circle* Analysis and algorithm design: print available around the symmetry circle graph. According to the circle equation: R* R = X* X+ Y* Y can calculate the correspondence between each point on the circle of rows and columns.* Questions: Implement the function y = x2 graphics and circle graphic overlay display.