题解 | 牛牛的圆
牛牛的圆
https://www.nowcoder.com/practice/75a202e826d048a39824ec694b5ce7e3
//#define _USE_MATH_DEFINES
#include <stdio.h>
#include <math.h>
int main() {
int r = 0;
double area = 0.0;
scanf("%d",&r);
area = M_PI * r * r;
printf("%.2f",area);
return 0;
}
