FZU 2099 魔法阵

手算。

#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;

double pi=acos(-1.0);
double L,R;

int main()
{
    int T; scanf("%d",&T);
    while(T--)
    {
        scanf("%lf%lf",&L,&R);
        double u=L/sqrt(3.0);
        double ans;
        if(u<=R)
        {
            ans=pi*R*R;
        }
        else if(R<=1.0/*L)
        {
            ans=sqrt(3.0)*L*L/;
        }
        else
        {
                double x=(*L-sqrt(-4.0/*L*L+*R*R))/;
                double s1=sqrt(3.0)*x*x;

                double h=sqrt(R*R-x*x);
                double s2=x*h;

                double alpha=*asin(x/R);
                double shan=alpha*R*R/;

                double xiao=s1+s2-shan;

                ans=pi*R*R+*xiao;
        }
        printf("%.2lf\n",ans);
    }
    return ;
}