HDU 2671 Can't be easier点直線の対称点について
978 ワード
/*
, A,B , min(PA+PB)=dis(A,B),
, B B`,min(PA+PB)=dis(A,B`)
*/
#include<iostream>
#include<cmath>
#include<cstdio>
using namespace std;
int main()
{
int c;
double k,x1,y1,x2,y2,x3,y3,x,y,dis,t,a,b;
cin>>c;
while(c--)
{
cin>>k>>x1>>y1>>x2>>y2>>x3>>y3;
if(x3!=1.0) t=k-k*x3+y3; // (1,t) (x3,y3) L
else t=2*k-k*x3+y3; // (2,t) (x3,y3) L
a=(1-x3)*(y2-y3)-(t-y3)*(x2-x3);
b=(1-x3)*(y1-y3)-(t-y3)*(x1-x3);
if(a*b>0) //a,b AC,BC L ,
{
y=(2*y3+(k*k-1)*y2+2*k*(x2-x3))/(k*k+1); // (CA+CB) k AB -1/k B`
x=x2-k*(y-y2);
dis=sqrt((x1-x)*(x1-x)+(y1-y)*(y1-y));
}
else dis=sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
printf("%.2lf
",dis);
}
return 0;
}