[Hdoj] 3400 line belt

Three points.

 1 #include <cstdio> 2 #include <cstring> 3 #include <cmath> 4  5 typedef struct { 6     double x, y; 7 } Point_t; 8  9 Point_t A, B, C, D;10 const double eps = 1.0e-8;11 double P, Q, R;12 13 double dist(Point_t a, Point_t b) {14     return sqrt((a.x-b.x)*(a.x-b.x) + (a.y-b.y)*(a.y-b.y));15 }16 17 double t_ab(Point_t a, Point_t b) {18     return dist(a, b)/P;19 }20 21 double t_cd(Point_t c, Point_t d) {22     return dist(c, d)/Q;23 }24 25 double t_oth(Point_t x, Point_t y) {26     return dist(x, y)/R;27 }28 29 double tri_cd(Point_t c, Point_t d, Point_t S) {30     Point_t left = c, right = d;31     Point_t p1, p2;32 33     while (dist(left, right) > eps) {34         p1.x = left.x*2.0/3.0 + right.x/3.0;35         p1.y = left.y*2.0/3.0 + right.y/3.0;36         p2.x = left.x/3.0 + right.x*2.0/3.0;37         p2.y = left.y/3.0 + right.y*2.0/3.0;38         if (t_oth(S, p1)+t_cd(p1, D) <= t_oth(S, p2)+t_cd(p2, D)) {39             right = p2;40         } else {41             left = p1;42         }43     }44     return t_oth(S, left) + t_cd(left, d);45 }46 47 double tri_ab(Point_t a, Point_t b) {48     Point_t left = a, right = b;49     Point_t p1, p2;50 51     while (dist(left, right) > eps) {52         p1.x = left.x*2.0/3.0 + right.x/3.0;53         p1.y = left.y*2.0/3.0 + right.y/3.0;54         p2.x = left.x/3.0 + right.x*2.0/3.0;55         p2.y = left.y/3.0 + right.y*2.0/3.0;56         if (t_ab(a, p1)+tri_cd(C, D, p1) <= t_ab(a, p2)+tri_cd(C, D, p2)) {57             right = p2;58         } else {59             left = p1;60         }61     }62     return t_ab(a, left) + tri_cd(C, D, left);63 }64 65 int main() {66     int t;67 68     scanf("%d", &t);69     while (t--) {70         scanf("%lf%lf%lf%lf",&A.x,&A.y,&B.x,&B.y);71         scanf("%lf%lf%lf%lf",&C.x,&C.y,&D.x,&D.y);72         scanf("%lf%lf%lf", &P, &Q, &R);73         printf("%.2lf\n", tri_ab(A, B));74     }75 76     return 0;77 }

 

[Hdoj] 3400 line belt