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 scanner = new Scanner(System.in); int num = scanner.nextInt(); System.out.printf("%.2f", 3.14 * (double) num * (double) num); } }