Morley’s Theorem（几何+UVA11178）

 

题意：Morley定理，求D、E、F的坐标

思路：没什么算法，就是几何的应用。注意旋转角就好了。

转载请注明出处：寻找&星空の孩子

 题目链接：UVA11178

 

 

#include<cstdio>
#include<cmath>
#define PI acos(-1.0)
using namespace std;

struct Point
{
    double x,y;
    Point(double x=0,double y=0):x(x),y(y){ }
 //   Point read_point() {scanf("%lf%lf",&this.x,&this.y);}
};
typedef Point Vector;
Vector operator + (Vector A,Vector B){return Vector(A.x+B.x,A.y+B.y);}
Vector operator - (Point A,Point B)  {return Vector(A.x-B.x,A.y-B.y);}
Vector operator * (Vector A,double p){return Vector(A.x*p,A.y*p);}
Vector operator / (Vector A,double p){return Vector(A.x/p,A.y/p);}

double Dot(Vector A,Vector B){return A.x*B.x+A.y*B.y;}
double length(Vector A){return sqrt(Dot(A,A));}
double Angle(Vector A,Vector B){return acos(Dot(A,B)/length(A)/length(B));}

double Cross(Vector A,Vector B){return A.x*B.y-B.x*A.y;}

Vector Rotate (Vector A,double rad)
{
    //其中rad为逆时针旋转角
    return Vector(A.x*cos(rad)-A.y*sin(rad),A.x*sin(rad)+A.y*cos(rad));
}

Point GetLineIntersection(Point P,Vector v,Point Q,Vector w)
{
    Vector u=P-Q;
    if(Cross(v,w))
    {
        double t=Cross(w,u)/Cross(v,w);//精度高的时候，考虑自定义分数类
        return P+v*t;
    }
//    else
 //       return ;
}

Point getD(Point A,Point B,Point C)
{
    Vector v1=C-B;
    double a1=Angle(A-B,v1);
    v1=Rotate(v1,a1/3);

    Vector v2=B-C;
    double a2=Angle(A-C,v2);
    v2=Rotate(v2,-a2/3);//-表示顺时针旋转;

    return GetLineIntersection(B,v1,C,v2);

}

Point read_point(Point &P)
{
    scanf("%lf%lf",&P.x,&P.y);
    return P;
}
int main()
{
    int T;
    Point A,B,C,D,E,F;
    scanf("%d",&T);
    while(T--)
    {
        A=read_point(A);
        B=read_point(B);
        C=read_point(C);

//        scanf("%lf%lf%lf%lf%lf%lf",&A.x,&A.y,&B.x,&B.y,&C.x,&C.y);
//        printf("%.6lf %.6lf %.6lf %.6lf %.6lf %.6lf\n",A.x,A.y,B.x,B.y,C.x,C.y);
        D=getD(A,B,C);
        E=getD(B,C,A);
        F=getD(C,A,B);
        printf("%.6lf %.6lf %.6lf %.6lf %.6lf %.6lf\n",D.x,D.y,E.x,E.y,F.x,F.y);
    }
    return 0;
}