Morley's Therorem（UVA11178+幾何）

尋找&星空の孩子發表於2015-04-17
REM

 題意：Morley定理，求D、E、F的座標

思路：沒什麼演算法，就是幾何的應用。注意旋轉角就好了。

轉載請註明出處：尋找&星空の孩子

 題目連結：UVA11178

 1 #include<cstdio>
 2 #include<cmath>
 3 #define PI acos(-1.0)
 4 using namespace std;
 5 
 6 struct Point
 7 {
 8     double x,y;
 9     Point(double x=0,double y=0):x(x),y(y){ }
10  //   Point read_point() {scanf("%lf%lf",&this.x,&this.y);}
11 };
12 typedef Point Vector;
13 Vector operator + (Vector A,Vector B){return Vector(A.x+B.x,A.y+B.y);}
14 Vector operator - (Point A,Point B)  {return Vector(A.x-B.x,A.y-B.y);}
15 Vector operator * (Vector A,double p){return Vector(A.x*p,A.y*p);}
16 Vector operator / (Vector A,double p){return Vector(A.x/p,A.y/p);}
17 
18 double Dot(Vector A,Vector B){return A.x*B.x+A.y*B.y;}
19 double length(Vector A){return sqrt(Dot(A,A));}
20 double Angle(Vector A,Vector B){return acos(Dot(A,B)/length(A)/length(B));}
21 
22 double Cross(Vector A,Vector B){return A.x*B.y-B.x*A.y;}
23 
24 Vector Rotate (Vector A,double rad)
25 {
26     //其中rad為逆時針旋轉角
27     return Vector(A.x*cos(rad)-A.y*sin(rad),A.x*sin(rad)+A.y*cos(rad));
28 }
29 
30 Point GetLineIntersection(Point P,Vector v,Point Q,Vector w)
31 {
32     Vector u=P-Q;
33     if(Cross(v,w))
34     {
35         double t=Cross(w,u)/Cross(v,w);//精度高的時候，考慮自定義分數類
36         return P+v*t;
37     }
38 //    else
39  //       return ;
40 }
41 
42 Point getD(Point A,Point B,Point C)
43 {
44     Vector v1=C-B;
45     double a1=Angle(A-B,v1);
46     v1=Rotate(v1,a1/3);
47 
48     Vector v2=B-C;
49     double a2=Angle(A-C,v2);
50     v2=Rotate(v2,-a2/3);//-表示順時針旋轉;
51 
52     return GetLineIntersection(B,v1,C,v2);
53 
54 }
55 
56 Point read_point(Point &P)
57 {
58     scanf("%lf%lf",&P.x,&P.y);
59     return P;
60 }
61 int main()
62 {
63     int T;
64     Point A,B,C,D,E,F;
65     scanf("%d",&T);
66     while(T--)
67     {
68         A=read_point(A);
69         B=read_point(B);
70         C=read_point(C);
71 
72 //        scanf("%lf%lf%lf%lf%lf%lf",&A.x,&A.y,&B.x,&B.y,&C.x,&C.y);
73 //        printf("%.6lf %.6lf %.6lf %.6lf %.6lf %.6lf\n",A.x,A.y,B.x,B.y,C.x,C.y);
74         D=getD(A,B,C);
75         E=getD(B,C,A);
76         F=getD(C,A,B);
77         printf("%.6lf %.6lf %.6lf %.6lf %.6lf %.6lf\n",D.x,D.y,E.x,E.y,F.x,F.y);
78     }
79     return 0;
80 }
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