hdu 5144 NPY and shot

http://acm.hdu.edu.cn/showproblem.php?pid=5144

题意：给你初始的高度和速度，然后让你求出水平的最远距离。

思路：三分枚举角度，然后根据公式求出水平距离。

 1 #include <cstdio>

 2 #include <cstring>

 3 #include <cmath>

 4 #include <algorithm>

 5 using namespace std;

 6 const double pi=acos(-1.0);

 7 const double eps=1e-6;

 8 const double g=9.8;

 9 

10 int t;

11 double h,v;

12 double ok(double x)

13 {

14      double xx=((double)(x/180))*pi;

15      double t1=v*sin(xx)/g;

16      double y=v*t1*sin(xx)-0.5*g*t1*t1;

17      double yy=y+h;

18      double t2=sqrt(yy*2/g);

19      double s=v*cos(xx)*(t1+t2);

20      return s;

21 }

22 

23 int main()

24 {

25     scanf("%d",&t);

26     while(t--)

27     {

28         scanf("%lf%lf",&h,&v);

29         double l=0,r=90;

30         double c;

31         while(r-l>eps)

32         {

33              double mid1=(r+l)/2;

34              double mid2=(l+mid1)/2;

35              if(ok(mid1)>=ok(mid2))

36              {

37                  c=mid1;

38                  l=mid2;

39              }

40              else

41                 r=mid1;

42         }

43         printf("%.2lf\n",ok(c));

44     }

45     return 0;

46 }

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