三分 HDU 5144

#include<stdio.h>
#include<algorithm>
#include<string.h>
#include<math.h>
using namespace std;

#define g 9.8
const double pi = 4*atan(1.0);
double v,h;

double f(double a)
{
        return v*cos(a)*v*sin(a)/g+v*cos(a)*sqrt(v*v*sin(a)*sin(a)/g/g+2*h/g);
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
    {

        scanf("%lf%lf",&h,&v);
        double l,r;
        l=0;
        r=pi/2;
        while(r-l>=1e-10)
        {
            double lm,rm;
            lm=l+(r-l)/3;
            rm=l+(r-l)*2/3;
            if(f(lm)>f(rm))
                r=rm;
            else
                l=lm;
        }
        printf("%.2lf\n",f(l));
    }

    return 0;
}