UVa 11178 - 计算几何初步

本题直接计算即可，“主要是看你会不会算”。。

抄了一通Rujia Liu的代码。。同样地。。方便好记然而效率比较低。。

所以先用着。。用熟了再参考黄学长的模板。。

// UVa 11178

#include <cstdio>
#include <algorithm>
#include <cmath>
using namespace std;

 int T;

 #define rep(i,a,b) for (int i=a; i<=b; i++)
 #define read(x) scanf("%d", &x)
 
 struct Point {
     double x, y;
     Point(double x=0, double y=0) : x(x), y(y) { }
 } A, B, C, D, E, F;
 
 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); }
 
 double Dot(Vector A, Vector B) { return A.x*B.x+A.y*B.y; }
 double Cross(Vector A, Vector B) { return A.x*B.y-A.y*B.x; }
 double Length(Vector A) { return sqrt(Dot(A, A)); }
 double Angel(Vector A, Vector B) { return acos(Dot(A, B)/Length(A)/Length(B)); }
 Vector Rotate(Vector A, double rad) {
     return Vector(A.x*cos(rad)-A.y*sin(rad), A.x*sin(rad)+A.y*cos(rad));
 }

 Point get_line_intersection(Point P, Vector v, Point Q, Vector w) {
     Vector u=P-Q;
     double t=Cross(w, u)/Cross(v, w);
     return P+v*t;
 }
 
 Point get_intersection(Point A, Point B, Point C) {
     Vector v1=C-B;
     double a1=Angel(A-B, v1);
     v1=Rotate(v1, a1/3);
     
     Vector v2=B-C;
     double a2=Angel(A-C, v2);
     v2=Rotate(v2, -a2/3);
     
     return get_line_intersection(B, v1, C, v2);
 }

 Point read_point() {
     double x, y;
     scanf("%lf %lf", &x, &y);
     return Point(x, y);
 }

int main()
{
    read(T);
    while (T--) {
        A=read_point(); B=read_point(); C=read_point();
        D=get_intersection(A, B, C);
        E=get_intersection(B, C, A);
        F=get_intersection(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;
}