[蓝桥杯] 圆的面积 入门

原题链接

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import java.util.Scanner;//导入Scanner类

public class Main {
    public static void main(String[] args) {
        double PI=3.14159265358979323;
        Scanner sc = new Scanner(System.in);
        int r = sc.nextInt();
        sc.close();
        System.out.printf("%.7f",r*r*PI);
    }
}