题解 | #牛牛的圆#
牛牛的圆
http://www.nowcoder.com/practice/75a202e826d048a39824ec694b5ce7e3
import java.util.Scanner; public class Main { public static void main(String[] args) { Scanner sc=new Scanner(System.in); int r=sc.nextInt(); System.out.printf("%.2f",3.14*r*r); } }