hdu 3400 Line belt

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 #include <cmath>
 5 using namespace std;
 6 const double eps=1e-8;
 7 
 8 int t;
 9 double p,q,r;
10 struct point
11 {
12      double x,y;
13 }a,b,c,d;
14 
15 double sqr(double x)
16 {
17     return x*x;
18 }
19 
20 double dis(double x1,double y1,double x2,double y2)
21 {
22     return sqrt(sqr(x1-x2)+sqr(y1-y2)+eps);
23 }
24 
25 double ok(double t1)
26 {
27     point pos;
28     pos.x=a.x+(b.x-a.x)*((t1*p)/dis(a.x,a.y,b.x,b.y));
29     pos.y=a.y+(b.y-a.y)*((t1*p)/dis(a.x,a.y,b.x,b.y));
30     double l1=0,r1=dis(c.x,c.y,d.x,d.y)/q;
31     while(r1-l1>eps)
32     {
33         double mid1=(r1+l1)/2;
34         double mid2=(mid1+r1)/2;
35         double x1=d.x+(c.x-d.x)*((mid1*q)/dis(c.x,c.y,d.x,d.y));
36         double y1=d.y+(c.y-d.y)*((mid1*q)/dis(c.x,c.y,d.x,d.y));
37         double x2=d.x+(c.x-d.x)*((mid2*q)/dis(c.x,c.y,d.x,d.y));
38         double y2=d.y+(c.y-d.y)*((mid2*q)/dis(c.x,c.y,d.x,d.y));
39         double d1=dis(pos.x,pos.y,x1,y1)/r;
40         double d2=dis(pos.x,pos.y,x2,y2)/r;
41         if(d1+mid1<=d2+mid2)
42         {
43             r1=mid2;
44         }
45         else
46             l1=mid1;
47     }
48     double xx=d.x+(c.x-d.x)*(l1*q)/dis(c.x,c.y,d.x,d.y);
49     double yy=d.y+(c.y-d.y)*(l1*q)/dis(c.x,c.y,d.x,d.y);
50     return dis(pos.x,pos.y,xx,yy)/r+t1+l1;
51 }
52 
53 int main()
54 {
55     scanf("%d",&t);
56     while(t--)
57     {
58         scanf("%lf%lf%lf%lf",&a.x,&a.y,&b.x,&b.y);
59         scanf("%lf%lf%lf%lf",&c.x,&c.y,&d.x,&d.y);
60         scanf("%lf%lf%lf",&p,&q,&r);
61         double ll=0,rr=dis(a.x,a.y,b.x,b.y)/p;
62         while(rr-ll>eps)
63         {
64             double mid1=(ll+rr)/2;
65             double mid2=(mid1+ll)/2;
66             if(ok(mid2)>=ok(mid1))
67             {
68                 ll=mid2;
69             }
70             else
71                 rr=mid1;
72         }
73         printf("%.2lf\n",ok(ll));
74     }
75 }