HDU 3756 Dome of Circus

#include <iostream>
#include <cmath>
using namespace std;

struct point
{
double x;
double y;
}p[10005];

int n;
double cal(double h)
{
double R=0;
for(int i=0;i<n;i++)
{
//R=max(R,h*p[i].x/(h-p[i].y));
if(R*(h-p[i].y)<h*p[i].x)
R=h*p[i].x/(h-p[i].y);
}
return R;
}

double binary_search(double left,double right)
{
double mid ,midmid,R1,R2;
while(fabs(right-left)>1e-8)
{
mid = (left+right)/2;
midmid = (mid + right)/2;
R1 = cal(mid);
R2 = cal(midmid);
if(mid*R1*R1>midmid*R2*R2)
{
left= mid;
}else
{
right = midmid;
}
}
return mid;
}
int main(int argc, const char *argv[])
{
int T;
scanf("%d",&T);
while(T--)
{
scanf("%d",&n);
double h = 0 , r = 0 ,Y;
for(int i=0;i<n;i++)
{
double x,y,z;
scanf("%lf%lf%lf",&x,&y,&p[i].y);
p[i].x = sqrt(x*x +y*y);
Y=max(p[i].y,Y);
}
r = binary_search(Y,1<<30);
printf("%.3lf %.3lf\n",r,cal(r));
}
return 0;
}