public class Yuan {
public static void main(String[] args) {
prinf(30);
}
//r圆的半径
public static void prinf(int r) {
//i代表每一行
for(int i=0;i<=2*r;i+=2) {
//圆上点到竖着半径的距离
long y = Math.ro
import java.util.Scanner;
public class HelloWorld{
public static void main(String[] args) {
System.out.println("请输入圆的半径：");
Scanner input = new Scanner(System.in);
double pi = 3.14;
double r
