【三分】Codeforces Round #403 (Div. 2, based on Technocup 2017 Finals) B. The Meeting Place Cannot Be Changed

三分显然，要注意EPS必须设成1e-6，设得再小一点都会TLE……坑炸了

#include<cstdio>
#include<algorithm>
#include<cmath>
using namespace std;
#define EPS 0.000001
int n,x[60010],v[60010];
double calc(double p)
{
	double res=0;
	for(int i=1;i<=n;++i)
	  res=max(res,fabs(p-(double)x[i])/(double)v[i]);
	return res;
}
int main()
{
//	freopen("b.in","r",stdin);
	scanf("%d",&n);
	for(int i=1;i<=n;++i)
	  scanf("%d",&x[i]);
	for(int i=1;i<=n;++i)
	  scanf("%d",&v[i]);
	double l=1.0,r=1000000000.0;
	while(r-l>EPS)
	  {
	  	double m1=l+(r-l)/3.0;
	  	double m2=r-(r-l)/3.0;
	  	double t1=calc(m1),t2=calc(m2);
	  	if(t1>t2)
	  	  l=m1;
	  	else
	  	  r=m2;
	  }
	printf("%.12lf\n",calc(l));
	return 0;
}