UVA - 11178 Morley's Theorem //几何初探

Output

For each line of input you should produce one line of output. This line contains six floating point numbers

separated by a single space. These six floating-point
actually means that the Cartesian coordinates of D, E and F are

respectively. Errors less than

will
be accepted.

Sample Input Output for Sample Input

2 

1 1 2 2 1 2 

0 0 100 0 50 50

#include <stdio.h>
#include <math.h>

#define PI 57.29577957855229 // 180/3.14159265
#define No 999999.9
#define MIN 1e-8

struct Point
{
double x;
double y;
};
struct Line
{
double k;
double b;
};

Point get_point(struct Line AB, double a, struct Line BC, double b,Point A, Point B);
Line get_line(struct Point a, struct Point b);
double get_agree(struct Point a, struct Point b, struct Point c);

int main()
{
Point A, B, C;
Line AB, BC, CA;
Point p1, p2, p3;

double a, b, c;
int t;

scanf("%d", &t);
while(t--)
{
scanf("%lf%lf%lf%lf%lf%lf", &A.x, &A.y, &B.x, &B.y, &C.x, &C.y);

a = get_agree(B, A, C);
b = get_agree(A, B, C);
c = get_agree(B, C, A);

AB = get_line(A, B);
BC = get_line(B, C);
CA = get_line(A, C);

p1 = get_point(BC, b, CA, c, B, C);
p2 = get_point(CA, c, AB, a, C, A);
p3 = get_point(AB, a, BC, b, A, B);

printf("%.6f %.6f %.6f %.6f %.6f %.6f\n", p1.x, p1.y, p2.x, p2.y, p3.x, p3.y);
}
return 0;
}
Point get_point(struct Line AB, double a, struct Line BC, double b, Point A, Point B)
{
Point p;

if(fabs(AB.k - No) > MIN)
{

AB.k = tan( (atan(AB.k)*PI + a/3.0)/PI );
}
else
{
AB.k = tan((90.0 + a/3.0)/PI);
}

if(fabs(BC.k - No) > MIN)
{
BC.k = tan( (atan(BC.k)*PI + (b/3.0)*2.0)/PI );
}
else
{
BC.k = tan((90.0 + (b/3.0)*2.0)/PI);
}
AB.b = A.y - AB.k*1.0*A.x;
BC.b = B.y - BC.k*1.0*B.x;

p.x = (BC.b - AB.b)/((AB.k - BC.k)*1.0);
p.y = AB.k * p.x*1.0 + AB.b;

return p;
}
Line get_line(struct Point a, struct Point b)
{
Line l;

if(fabs(b.x-a.x) > MIN)
{
if(fabs(b.y-a.y) < MIN)
l.k = 0.0;
else
l.k = (b.y - a.y)/((b.x - a.x)*1.0);
l.b = a.y - l.k * a.x*1.0;
}
else
{
l.k = No;
l.b = a.y;
}
return l;
}
double get_agree(struct Point a, struct Point b, struct Point c)
{
Point ab, bc;
double A;

ab.x = a.x - b.x;
ab.y = a.y - b.y;

bc.x = c.x - b.x;
bc.y = c.y - b.y;

A = (ab.x*bc.x + ab.y*bc.y)/(( sqrt(ab.x*ab.x + ab.y*ab.y)*sqrt(bc.x*bc.x + bc.y*bc.y) )*1.0);

return acos(A)*PI;

}