UVa 11178计算几何 模板题

#include<cstdio>
#include<cstring>
#include<cmath>
#include<iostream>
#include<algorithm>
#include<queue>
#include<vector>
using namespace std;

struct Point{
    double x,y;
    Point(double x=, double y=) : x(x),y(y){ }    //构造函数
};
typedef Point Vector;

Vector operator + (Vector A , Vector B){return Vector(A.x+B.x,A.y+B.y);}
Vector operator - (Vector A , Vector 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);}

bool operator < (const Point& a,const Point& b){
    return a.x < b.x ||( a.x == b.x && a.y < b.y);
}
const double eps = 1e-;
int dcmp(double x){
    if(fabs(x) < eps) return ;
    else              return x <  ? - : ;
}
bool operator == (const Point& a, const Point& b){
    return dcmp(a.x - b.x) ==  && dcmp(a.y - b.y) == ;
}

///向量（x,y）的极角用atan2(y,x);
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 - A.y * B.x; }
double Area2(Point A,Point B,Point C) { return Cross(B-A,C-A); }

///向量的逆时针旋转，rad 为旋转的角；
Vector Rotate(Vector A, double rad) { return Vector(A.x*cos(rad)-A.y*sin(rad),A.x*sin(rad)+A.y*cos(rad)); }
///特殊的，下面函数计算向量的单位法向量，即左旋90，在长度归一化；
Vector Normal(Vector A){
    double L = Length(A);
    return Vector(-A.y/L, A.x/L);
}

///直线用参数式 P = P'+ t * v；P'为直线上一点，v为方向向量；
///t不受限制，为直线，t>0 为射线， 0=<t<=1为线段；
///推导暂时不会,下面计算直线P+tv和Q+tw的交点。调用前先确保两直线有唯一交点；即判定Cross(v,w) 非0；
Point GetLineIntersecion(Point P, Vector v,Point Q,Vector w){
    Vector u = P - Q;
    double t = Cross(w,u)/Cross(v,w);
    return P + v*t;
}

///求点到直线的距离，利用h*|AB| == AB(向量) * AP(向量)；
double DistanceToLine(Point P,Point A,Point B){
    Vector v1 = B - A, v2 = P - A;
    return fabs(Cross(v1,v2)) / Length(v1);
}

///求点P到线段AB的距离，先看Q点在线段外还是内；利用点积就可以，
double DistanceToSegment(Point P,Point A,Point B){
    if(A == B)  return Length(P-A);
    Vector v1 = B - A,v2 = P - A,v3 = P - B;
    if(dcmp(Dot(v1,v2)) < )       return Length(v2);
    else if(dcmp(Dot(v1,v3) > ))  return Length(v2);
    else    return  fabs(Cross(v1,v2))/Length(v1);
}
///如果要求Q的话：（当然满足Q在线段内）,由公式Dot(v,P-(A+t'*v)) == 0 推出；
Point GetLineProjection(Point P,Point A,Point B){
    Vector v = B - A;
    return A + v * (Dot(v,P-A)/Dot(v,v));
}

///判定线段是否规范相交；
bool SegmentProperIntersection(Point a1,Point a2,Point b1,Point b2){
    double c1 = Cross(a2-a1,b1-a1), c2 = Cross(a2-a1,b2-a1),
           c3 = Cross(b2-b1,a1-b1), c4 = Cross(b2-b1,a2-b1);
    return dcmp(c1) * dcmp(c2) <  && dcmp(c3) * dcmp(c4) < ;
}
///如果允许在端点处相交：c1和c2都是0，表示两线段共线；如果只有其中一个为0，则一条线段的端点在另一条线段上；
///下面的代码判断一个点P是否在一条线段AB上；
bool OnSegment(Point P,Point A,Point B){
    return dcmp(Cross(A-P,B-P)) ==  && dcmp(Dot(P-A,P-B)) < ;
}

///多边形
///求面积
double PolygonArea(Point* p,int n){
    double area = ;
    for(int i=;i<n-;i++){
        area += Cross(p[i]-p[],p[i+]-p[]);
    }
    return area/;
}

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

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

    return GetLineIntersecion(B,v1,C,v2);
}
Point read_point(){
    Point A;
    scanf("%lf %lf",&A.x,&A.y);
    return A;
}

int main()
{
    //freopen("input.txt","r",stdin);
    //freopen("output.txt","w",stdout);
    int T;
    cin>>T;
    Point A,B,C,D,E,F;
    while(T--){
       A = read_point();
       B = read_point();
       C = read_point();
       D = GetOnePoint(A,B,C);
       E = GetOnePoint(B,C,A);
       F = GetOnePoint(C,A,B);
       printf("%.6lf %.6lf %.6lf %.6lf %.6lf %.6lf\n",D.x,D.y,E.x,E.y,F.x,F.y);
    }
    return ;
}