【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
", tri_ab(A, B));
    }

    return 0;
}