【bzoj1857】传送带——三分套三分

#include<cstdio>
#include<cstring>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstdlib>
#define eps 1e-3
using namespace std;
struct point 
{
    int x,y;
}a,b,c,d;
int p,q,r;
double dis(double x1,double y1,double x2,double y2)
{
    return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));
}
double cal(double x,double y)
{
    double lx=c.x,ly=c.y,rx=d.x,ry=d.y;
    double x1,y1,x2,y2,t1,t2;
    double ab=dis(x,y,a.x,a.y)/p;
    while(fabs(rx-lx)>eps||fabs(ry-ly)>eps)
    {
        x1=lx+(rx-lx)/3;y1=ly+(ry-ly)/3;
        x2=lx+(rx-lx)/3*2;y2=ly+(ry-ly)/3*2;
        t1=ab+dis(x1,y1,x,y)/r+dis(d.x,d.y,x1,y1)/q;
        t2=ab+dis(x2,y2,x,y)/r+dis(d.x,d.y,x2,y2)/q;
        if(t1>t2)lx=x1,ly=y1;
        else rx=x2,ry=y2;
    }
    return ab+dis(lx,ly,x,y)/r+dis(d.x,d.y,lx,ly)/q;
}
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;
}
int main()
{
    a.x=read();a.y=read();b.x=read();b.y=read();
    c.x=read();c.y=read();d.x=read();d.y=read();
    p=read();q=read();r=read();
    double lx=a.x,ly=a.y,rx=b.x,ry=b.y;
    double x1,y1,x2,y2,t1,t2;
    while(fabs(rx-lx)>eps||fabs(ry-ly)>eps)
    {
        x1=lx+(rx-lx)/3;y1=ly+(ry-ly)/3;
        x2=lx+(rx-lx)/3*2;y2=ly+(ry-ly)/3*2;
        t1=cal(x1,y1);t2=cal(x2,y2);
        if(t1>t2)lx=x1,ly=y1;
        else rx=x2,ry=y2;
    }
    printf("%.2lf",cal(lx,ly));
    return 0;
}