hdu 2289 Cup

链接：http://acm.hdu.edu.cn/showproblem.php?pid=2289

细节问题：

1、r为下底，R为上底，r<=R

2、v==0直接输出"0"

3、ans>h直接输出h

4、圆台体积公式：PI*h*(r*r+r*R+R*R) / 3; 

 1 #include <cstdio>
 2 #include <cmath>
 3 #define PI (double)acos(-1.0)
 4 
 5 int main()
 6 {
 7     int t;
 8     double r1,r2,h,v,x,r3,vv,left,right,y;
 9     scanf("%d",&t);
10     while(t--)
11     {
12         scanf("%lf%lf%lf%lf",&r1,&r2,&h,&v);
13         if(v<1e-12)
14             printf("0.000000\n");
15         else if((r2-r1)<1e-12)
16         {
17             double ans = v / (r1 * r1 * PI);
18             if(ans>h)
19                 printf("%.6lf\n",h);
20             else
21                 printf("%.6lf\n",ans);
22         }
23         else
24         {
25             left = 0; right = h;
26             while(right-left>1e-12)
27             {
28                 y = (left + right) / 2;
29                 r3 = r1 + (r2 - r1) * y / h;
30                 vv = PI * y * (r3*r3 + r1*r1 + r1*r3) / 3;
31                 if(vv>v)
32                     right = y;
33                 else
34                     left = y;
35             }
36             printf("%.6lf\n",y);
37         }
38     }
39     return 0;
40 }