【BZOJ-1857】传送带 三分套三分

#include<iostream>
#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath> 
using namespace std;
int read()
{
    int x=0,f=1; char ch=getchar();
    while (ch<‘0‘ || ch>‘9‘) {if (ch==‘-‘) f=-1; ch=getchar();}
    while (ch>=‘0‘ && ch<=‘9‘) {x=x*10+ch-‘0‘; ch=getchar();}
    return x*f;
}
#define eps 1e-3
int Ax,Ay,Bx,By,Cx,Cy,Dx,Dy,P,Q,R;
double dist(double x1,double y1,double x2,double y2)
{
    return sqrt((x2-x1)*(x2-x1)+(y2-y1)*(y2-y1));
}
double Calc(double X,double Y)
{
    double Lx=Cx,Ly=Cy,Rx=Dx,Ry=Dy;
    while (fabs(Rx-Lx)>eps || fabs(Ry-Ly)>eps)
        {
            double Mx1=Lx+(Rx-Lx)/3,My1=Ly+(Ry-Ly)/3,Mx2=Lx+(Rx-Lx)/3*2,My2=Ly+(Ry-Ly)/3*2;
            double LL=dist(Ax,Ay,X,Y)/P+dist(X,Y,Mx1,My1)/R+dist(Mx1,My1,Dx,Dy)/Q;
            double RR=dist(Ax,Ay,X,Y)/P+dist(X,Y,Mx2,My2)/R+dist(Mx2,My2,Dx,Dy)/Q;
            if (LL>RR) Lx=Mx1,Ly=My1;
                else Rx=Mx2,Ry=My2;
        }
    return dist(Ax,Ay,X,Y)/P+dist(X,Y,Lx,Ly)/R+dist(Lx,Ly,Dx,Dy)/Q;
}
int main()
{
    Ax=read(); Ay=read(); Bx=read(); By=read();
    Cx=read(); Cy=read(); Dx=read(); Dy=read();
    P=read(); Q=read(); R=read();
    double Lx=Ax,Ly=Ay,Rx=Bx,Ry=By;
    while (fabs(Rx-Lx)>eps || fabs(Ry-Ly)>eps)
        {
            double Mx1=Lx+(Rx-Lx)/3,Mx2=Lx+(Rx-Lx)/3*2,My1=Ly+(Ry-Ly)/3,My2=Ly+(Ry-Ly)/3*2;
            double LL=Calc(Mx1,My1),RR=Calc(Mx2,My2);
            if (LL>RR) Lx=Mx1,Ly=My1;
                else Rx=Mx2,Ry=My2;
        }
    printf("%.2lf\n",Calc(Lx,Ly));
    return 0;
}