二分搜索 HDOJ 2289 Cup

 

题目传送门

 1 /*  2  二分搜索：枚举高度，计算体积与给出的比较。  3 */  4 #include <cstdio>  5 #include <algorithm>  6 #include <cstring>  7 #include <cmath>  8 using namespace std;  9 10 const int MAXN = 1e3 + 10; 11 const int INF = 0x3f3f3f3f; 12 const double EPS = 1e-8; 13 const double PI = acos (-1.0); 14 double r, R, H, V; 15 double x; 16 17 double cal(double h1) { 18 double u = r + (R - r) * h1 / H; //上底 19 double V1 = PI / 3.0 * h1 * (r * r + r * u + u * u); //圆台计算公式 20 return V1; 21 } 22 23 int main(void) { //HDOJ 2289 Cup 24 //freopen ("HDOJ_2289.in", "r", stdin); 25 26 int T; scanf ("%d", &T); 27 while (T--) { 28 scanf ("%lf%lf%lf%lf", &r, &R, &H, &V); 29 double mid; 30 double low = 0, upp = H; 31 while (upp - low > EPS) { 32 mid = (low + upp) / 2; 33 if (cal (mid) - V > EPS) upp = mid; 34 else low = mid; 35  } 36 printf ("%.6f\n", mid); 37  } 38 39 return 0; 40 }