求条，hack不过,玄关

#include <bits/stdc++.h>
using namespace std;
double inf=1e18;
double d[200][200],x[200],y[200],a[200],a1,a2=inf;
char g[200][200];
int main(){
	int n;
	cin>>n;
	for (int i=1;i<=n;i++)
    {
		for(int j=1;j<=n;j++)
        {
            if(i!=j)
			d[i][j]=inf;
            else
            d[i][j]=0;
		}
	}
	for(int i=1;i<=n;i++)
    {
	    cin>>x[i]>>y[i];
	}
	for(int i=1;i<= n;i++)
    {
		for(int j=1;j<=n;j++)
        {
			cin>>g[i][j];
			if(g[i][j]=='1')
            {
				d[i][j]=sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j]));
			}			
		}
	}
	for(int k=1;k<=n;k++)
    {
		for(int i=1;i<=n;i++)
        {
			for(int j=1;j<=n;j++)
            {
				d[i][j]=min(d[i][j],d[i][k]+d[k][j]);
			}
		}
	}
	for(int i=1;i<=n;i++)
    {
		for(int j=1;j<=n;j++)
        {
			if(d[i][j]<inf/2)
            {
				a[i]=max(a[i],d[i][j]);
			}
		}
		a1=max(a1,a[i]);
	}
	for(int i=1;i<=n;i++)
    {
		for(int j=1;j<=n;j++)
        {
			if(d[i][j]>inf/2)
            {
				a2=min(a2,a[i]+a[j]+sqrt((x[i]-x[j])*(x[i]-x[j])+(y[i]-y[j])*(y[i]-y[j])));
			}
		}
	}
	printf("%.6lf",max(a1,a2));
	return 0;
}