hdu 多校第五场 E Everything Has Changed（6354）

余弦定理大法好w，瞎套模板不可取ORZ

#include 
#include 
using namespace std;
const double pi = acos(-1.0);
const double eps = 1e-10;
int dcmp(double x)
{
    if (fabs(x) < eps)
        return 0;
    else
        return x < 0 ? -1 : 1;
}
int main()
{
    //freopen("in.txt","r",stdin);
    int T;
    scanf("%d",&T);
    while(T--){
        int m;
        double R;
        scanf("%d%lf",&m,&R);
        double ans = 2*pi*R; 
        for(int i = 0; i0) continue; //内含
            double t = acos((R*R+d*d-r*r)/(2*R*d)); //printf("%lf\n",t);
            ans -= 2*t*R; //printf("%lf\n",ans);
            t = acos((r*r+d*d-R*R)/(2*r*d));
            ans +=2*t*r;
        }
        printf("%.20lf\n",ans);
    }
    return 0;
}