三分 POJ3737

#include <iostream>
#include <cstdio>
#include <cmath>

using namespace std;

double pi=acos(-1.0);
double s;

double f(double x)
{
    return pi*x*x*sqrt((s-pi*x*x)/(pi*x)*(s-pi*x*x)/(pi*x)-x*x)/3;
}

bool test(double tl,double tr)
{
    if(f(tl)<f(tr))
        return true;
    else
        return false;
}

int main()
{
    while(scanf("%lf",&s)!=EOF)
    {
        double l=0;
        double r=sqrt(s/(2*pi));
        while(r-l>1e-8)
        {
            double tl=l+(r-l)/3;
            double tr=r-(r-l)/3;
            if(test(tl,tr))
            {
                l=tl;
            }
            else
            {
                r=tr;
            }
        }
        double h=sqrt((s-pi*l*l)/(pi*l)*(s-pi*l*l)/(pi*l)-l*l);
        printf("%.2lf
",f(l));
        printf("%.2lf
",h);
        printf("%.2lf
",l);
    }
    return 0;
}