#include<stdio.h>
#include<math.h>
#define PI acos(-1.0)
#define EP 1e-8
int n,r;
struct TPoint
{
	double x,y;
};

TPoint point[1001];

double AreaOfPolygon(TPoint P[], int n)
{
	int i;
	double s = 0.0;
	if (n < 3) return 0.0;
	for (i = 0; i < n; i++)
		s += P[i].x * P[(i + 1) % n].y - P[i].y * P[(i + 1) % n].x;
	return fabs(s) / 2.0;
}

int main()
{
	freopen("a.in","r",stdin);
	double len=0.0;
	int i;
	scanf("%d %d",&n,&r);
	for(i=0;i<n;i++)
	{
		scanf("%lf %lf",&point[i].x,&point[i].y);
	}
	len = AreaOfPolygon(point, n);
	if(n>=2)
		len +=2.0*PI*r;
	if(n==2)
		len+=(point[0].x-point[1].x)*(point[0].x-point[1].x)+(point[0].y-point[1].y)*(point[0].y-point[1].y);
	printf("%.2lf\n",len);
	return 0;
}

• ft................................... (832) frkstyc 2005-07-23 22:10:48
  • 你算面积干什么！！！！ (0) frkstyc 2005-07-23 22:11:41
    • 昏 (0) sothink 2005-07-23 22:12:37
      • sample居然能过 (0) frkstyc 2005-07-23 22:13:35
        • Re:sample居然能过。。太假了， (0) sothink 2005-07-23 22:17:17
    • 四年前帖子，搞笑 (0) kanovy 2009-07-16 11:59:19
      • Re:四年前帖子，搞笑 (8) 120302508 2013-01-18 14:21:22
  • Re:ft？？？？？ for what？ (0) sothink 2005-07-23 22:11:42