Codeforces Round #172 (Div. 2) C.Rectangle Puzzle(几何)

题目链接

注意h > w的时候交换，还有就是注意一下转化double，错了好几次。。。算法就是解方程。。精度倒是不卡。

 1 #include <cstdio>

 2 #include <cstring>

 3 #include <cmath>

 4 #include <string>

 5 using namespace std;

 6 #define PI 3.1415926535898

 7 #define eps 1e-13

 8 double fun(double x)

 9 {

10     return x*PI/180;

11 }

12 int main()

13 {

14     int h,w,a,t;

15     double k1,k2,x,y,ha,sp,ans;

16     scanf("%d%d%d",&w,&h,&a);

17     if(h > w)

18     {

19         t = h;

20         h = w;

21         w = t;

22     }

23     ha = fun(a);

24     if(ha > fun(90.0))

25     {

26         ha = PI - ha;

27     }

28     sp = 2*(atan(h*1.0/w));

29     if(ha < sp)

30     {

31         k1 = (1 + 1/cos(ha));

32         k2 = tan(ha);

33         x = (h*k1-w*k2);

34         y = (h*k2-w*k1);

35         ans = (double)h*w - k2*(x*x + y*y)/((k1*k1-k2*k2)*(k1*k1-k2*k2));

36     }

37     else

38     {

39         ans = (double)h*h/sin(ha);

40     }

41     printf("%lf\n",ans+eps);

42     return 0;

43 }