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。

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 1 /*

 2 Author:Zhaofa Fang

 3 Lang:C++

 4 */

 5 #include <cstdio>

 6 #include <cstdlib>

 7 #include <sstream>

 8 #include <iostream>

 9 #include <cmath>

10 #include <cstring>

11 #include <algorithm>

12 #include <string>

13 #include <utility>

14 #include <vector>

15 #include <queue>

16 #include <stack>

17 #include <map>

18 #include <set>

19 using namespace std;

20 

21 typedef long long ll;

22 #define DEBUG(x) cout<< #x << ':' << x << endl

23 #define REP(i,n) for(int i=0;i < (n);i++)

24 #define REPD(i,n) for(int i=(n-1);i >= 0;i--)

25 #define FOR(i,s,t) for(int i = (s);i <= (t);i++)

26 #define FORD(i,s,t) for(int i = (s);i >= (t);i--)

27 #define PII pair<int,int>

28 #define PB push_back

29 #define MP make_pair

30 #define ft first

31 #define sd second

32 #define lowbit(x) (x&(-x))

33 #define INF (1<<30)

34 

35 

36 

37 const double PI = acos(-1);

38 double volume(double r,double R,double h)

39 {

40     return PI*h*(R*R+R*r+r*r)/3;

41 }

42 

43 int main()

44 {

45     //freopen("in","r",stdin);

46     //freopen("out","w",stdout);

47     int T;

48     scanf("%d",&T);

49     while(T--)

50     {

51         double r,R,H,V;

52         scanf("%lf%lf%lf%lf",&r,&R,&H,&V);

53         double h = r*H/(R-r);

54         if(r == R)h = 0;

55         double le=0,ri=H,hx;

56         while(fabs(ri-le)>1e-8)

57         {

58             hx = (le+ri)/2.0;

59             double rx = r*(h+hx)/h;

60             if(h == 0)rx = r;

61             if(volume(r,rx,hx)<V)le = hx+1e-8;

62             else ri = hx-1e-8;

63         }

64         printf("%.6f\n",hx);

65     }

66     return 0;

67 }