bzoj1857: [Scoi2010]传送带

#include<cmath>
#include<cstdio>
#include<algorithm>
using namespace std;

int read_p,read_ca,read_f;
inline int read(){
    read_p=0;read_ca=getchar();read_f=1;
    while(read_ca<‘0‘||read_ca>‘9‘) {if (read_ca==‘-‘) read_f=-1;read_ca=getchar();}
    while(read_ca>=‘0‘&&read_ca<=‘9‘) read_p=read_p*10+read_ca-48,read_ca=getchar();
    return read_p*read_f;
}
int xa,ya,xb,yb,xc,yc,xd,yd,p,q,r;
long double z1,z2;
inline double g(double a,double b){
    double xx1,yy1,xx2,yy2,zz1,zz2;
    zz1=a/z1;zz2=b/z2;
    xx1=xa+(xb-xa)*zz1;
    yy1=ya+(yb-ya)*zz1;
    xx2=xd+(xc-xd)*zz2;
    yy2=yd+(yc-yd)*zz2;
    return a/p+b/q+sqrt((xx2-xx1)*(xx2-xx1)+(yy2-yy1)*(yy2-yy1))/r;
}
inline double f(double x){
    double l=0,r=z2,mid1,mid2,w;
    while (r-l>=1e-10){
        w=(r-l)/3.0;mid1=l+w;mid2=mid1+w;
        if (g(x,mid1)>g(x,mid2)) l=mid1;else r=mid2;
    }
    return g(x,l);
}
int main(){
    /*freopen("a.in","r",stdin);
    freopen("a.out","w",stdout);*/
    xa=read();ya=read();xb=read();yb=read();xc=read();yc=read();xd=read();yd=read();
    z1=sqrt((xb-xa)*(xb-xa)+(yb-ya)*(yb-ya));z2=sqrt((xd-xc)*(xd-xc)+(yd-yc)*(yd-yc));
    p=read();q=read();r=read();
    double l=0,r=z1,mid1,mid2,w;
    while (r-l>1e-10){
        w=(r-l)/3.0;mid1=l+w;mid2=mid1+w;
        if (f(mid1)>f(mid2)) l=mid1;else r=mid2;
    }
    printf("%.2lf\n",f(l));
}