【HDOJ】3400 Line belt

三分。

 #include <cstdio>
 #include <cstring>
 #include <cmath>

 typedef struct {
     double x, y;
 } Point_t;

 Point_t A, B, C, D;
 const double eps = 1.0e-8;
 double P, Q, R;

 double dist(Point_t a, Point_t b) {
     return sqrt((a.x-b.x)*(a.x-b.x) + (a.y-b.y)*(a.y-b.y));
 }

 double t_ab(Point_t a, Point_t b) {
     return dist(a, b)/P;
 }

 double t_cd(Point_t c, Point_t d) {
     return dist(c, d)/Q;
 }

 double t_oth(Point_t x, Point_t y) {
     return dist(x, y)/R;
 }

 double tri_cd(Point_t c, Point_t d, Point_t S) {
     Point_t left = c, right = d;
     Point_t p1, p2;

     while (dist(left, right) > eps) {
         p1.x = left.x*2.0/3.0 + right.x/3.0;
         p1.y = left.y*2.0/3.0 + right.y/3.0;
         p2.x = left.x/3.0 + right.x*2.0/3.0;
         p2.y = left.y/3.0 + right.y*2.0/3.0;
         if (t_oth(S, p1)+t_cd(p1, D) <= t_oth(S, p2)+t_cd(p2, D)) {
             right = p2;
         } else {
             left = p1;
         }
     }
     return t_oth(S, left) + t_cd(left, d);
 }

 double tri_ab(Point_t a, Point_t b) {
     Point_t left = a, right = b;
     Point_t p1, p2;

     while (dist(left, right) > eps) {
         p1.x = left.x*2.0/3.0 + right.x/3.0;
         p1.y = left.y*2.0/3.0 + right.y/3.0;
         p2.x = left.x/3.0 + right.x*2.0/3.0;
         p2.y = left.y/3.0 + right.y*2.0/3.0;
         if (t_ab(a, p1)+tri_cd(C, D, p1) <= t_ab(a, p2)+tri_cd(C, D, p2)) {
             right = p2;
         } else {
             left = p1;
         }
     }
     return t_ab(a, left) + tri_cd(C, D, left);
 }

 int main() {
     int t;

     scanf("%d", &t);
     while (t--) {
         scanf("%lf%lf%lf%lf",&A.x,&A.y,&B.x,&B.y);
         scanf("%lf%lf%lf%lf",&C.x,&C.y,&D.x,&D.y);
         scanf("%lf%lf%lf", &P, &Q, &R);
         printf("%.2lf\n", tri_ab(A, B));
     }

     return ;
 }