100分求助！！

#include<iostream>
#include<cmath>
#include<cstring>
#include<string>
#include<algorithm>
#include<cstdio>
#include<stdio.h>
using namespace std;
double maxn=99999999,minn=9999999;
double x[205],y[205],map[1005][1005],m[100005];
double dis(int i,int j)
{
	return sqrt(pow(abs(x[i]-x[j]),2)+pow(abs(y[i]-y[j]),2));
}
int main()
{
	int i,j,k,n;
	char c;
	cin>>n;
	for(i=1;i<=n;i++)
		cin>>x[i]>>y[i];
	for(i=1;i<=n;i++)
		for(j=1;j<=n;j++)
		{
			cin>>c;
			if(c=='1')
				map[i][j]=dis(i,j);
			else
				map[i][j]=maxn;
		}
	for(k=1;k<=n;k++)
		for(i=1;i<=n;i++)
			for(j=1;j<=n;j++)
				if(i!=j&&j!=k&&i!=k)
				{
					if(map[i][j]>map[i][k]+map[k][j])
						map[i][j]=map[i][k]+map[k][j];
				}
	memset(m,0,sizeof(m));
	for(i=1;i<=n;i++)
		for(j=1;j<=n;j++)
			if(map[i][j]<maxn&&m[i]<map[i][j])
				m[i]=map[i][j];
	for(i=1;i<=n;i++)
		for(j=1;j<=n;j++)
			if(i!=j&&map[i][j]==maxn)
			{
				if(minn>m[i]+m[j]+dis(i,j))
					minn=m[i]+m[j]+dis(i,j);
			}
	for(i=1;i<=n;i++)
		if(m[i]>minn)
			minn=m[i];
	printf("%.6lf",minn);
	return 0;
}