OJ-Problems-Source/HDOJ/3834_autoAC.cpp

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#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<algorithm>
const double eps=1e-12;
const double pi=acos(-1.0);
using namespace std;
typedef long long ll;
inline double sqr(double x)
{
return x*x;
}
struct point
{
double x, y, r;
point(){}
point(double _x, double _y, double _r){x=_x;y=_y;r=_r;}
void read(){scanf("%lf%lf%lf", &x, &y, &r);}
point operator -(const point &tp)const
{
return point(x-tp.x, y-tp.y, r-tp.r);
}
point operator +(const point &tp)const
{
return point(x+tp.x, y+tp.y, r+tp.r);
}
point operator *(const double &k)const
{
return point(x*k, y*k, r*k);
}
}table, ball;
double dx, dy, tot;
int cross(point op, point sp, point ep)
{
double ans=(sp.y-op.y)*(ep.x-op.x)-(ep.y-op.y)*(sp.x-op.x);
if(ans>eps)return 1;
return -1;
}
double angle(point a, point b)
{
double area=a.x*b.x+a.y*b.y;
double ablen=sqrt((a.x*a.x+a.y*a.y)*(b.x*b.x+b.y*b.y));
return acos(area/ablen);
}
int main()
{
int ca;
scanf("%d", &ca);
while(ca-->0)
{
table.read();
ball.read();
scanf("%lf%lf%lf", &dx, &dy, &tot);
ball.x-=table.x;
ball.y-=table.y;
table.r-=ball.r;
double a=sqr(dx)+sqr(dy);
double b=2.0*(ball.x*dx*1.0+ball.y*dy*1.0);
double c=sqr(ball.x)+sqr(ball.y)-sqr(table.r);
double sti=(sqrt(sqr(b)-4.0*a*c)-b)/(2.0*a);
if(sti-tot>eps)
{
printf("%.1lf %.1lf\n", (ball.x+tot*dx+table.x), (ball.y+tot*dy+table.y));
continue;
}
point zero=point(0, 0, 0);
point first=point(sti*dx+ball.x, sti*dy+ball.y, 0);
int dir=cross(zero, first, ball);
double ref=angle(ball-first, zero-first);
double dis=cos(ref)*table.r*2;
double v=sqrt(dx*dx+dy*dy);
tot-=sti;
double len=tot*v;
double dti=len/dis;
ll lti=(ll)(dti+eps);
double perti=dis/v;
double left=tot-perti*lti;
double pang=(pi-2*ref)*lti;
double stang=atan2(first.y, first.x);
stang=stang+pang*dir;
point now=point(cos(stang)*table.r, sin(stang)*table.r, 0);
double vang=stang+(pi-2*ref)*dir;
point next=point(cos(vang)*table.r, sin(vang)*table.r, 0);
double rate=left/perti;
point vec=next-now;
now=now+(vec*rate);
printf("%.1lf %.1lf\n", now.x+table.x, now.y+table.y);
}
return 0;
}