hdu 2289 cup(二分搜索)

注意：当杯子为圆柱时也要二分，不能直接算。

/*
Author:Zhaofa Fang
Lang:C++
*/
#include <cstdio>
#include <cstdlib>
#include <sstream>
#include <iostream>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <string>
#include <utility>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <set>
using namespace std;

typedef long long ll;
#define DEBUG(x) cout<< #x << ':' << x << endl
#define REP(i,n) for(int i=0;i < (n);i++)
#define REPD(i,n) for(int i=(n-1);i >= 0;i--)
#define FOR(i,s,t) for(int i = (s);i <= (t);i++)
#define FORD(i,s,t) for(int i = (s);i >= (t);i--)
#define PII pair<int,int>
#define PB push_back
#define MP make_pair
#define ft first
#define sd second
#define lowbit(x) (x&(-x))
#define INF (1<<30)



const double PI = acos(-1);
double volume(double r,double R,double h)
{
    return PI*h*(R*R+R*r+r*r)/3;
}

int main()
{
    //freopen("in","r",stdin);
    //freopen("out","w",stdout);
    int T;
    scanf("%d",&T);
    while(T--)
    {
        double r,R,H,V;
        scanf("%lf%lf%lf%lf",&r,&R,&H,&V);
        double h = r*H/(R-r);
        if(r == R)h = 0;
        double le=0,ri=H,hx;
        while(fabs(ri-le)>1e-8)
        {
            hx = (le+ri)/2.0;
            double rx = r*(h+hx)/h;
            if(h == 0)rx = r;
            if(volume(r,rx,hx)<V)le = hx+1e-8;
            else ri = hx-1e-8;
        }
        printf("%.6f\n",hx);
    }
    return 0;
}