二分搜索 HDOJ 2289 Cup

题目传送门

 /*
     二分搜索：枚举高度，计算体积与给出的比较。
 */
 #include <cstdio>
 #include <algorithm>
 #include <cstring>
 #include <cmath>
 using namespace std;

 const int MAXN = 1e3 + ;
 const int INF = 0x3f3f3f3f;
 const double EPS = 1e-;
 const double PI = acos (-1.0);
 double r, R, H, V;
 double x;

 double cal(double h1)    {
     double u = r + (R - r) * h1 / H;        //上底
     double V1 = PI / 3.0 * h1 * (r * r + r * u + u * u);    //圆台计算公式
     return V1;
 }

 int main(void)  {       //HDOJ 2289 Cup
     //freopen ("HDOJ_2289.in", "r", stdin);

     int T;  scanf ("%d", &T);
     while (T--) {
         scanf ("%lf%lf%lf%lf", &r, &R, &H, &V);
         double mid;
         double low = , upp = H;
         while (upp - low > EPS)  {
             mid = (low + upp) / ;
             if (cal (mid) - V > EPS)    upp = mid;
             else low = mid;
         }
         printf ("%.6f\n", mid);
     }

     return ;
 }