不开O2就AC了，开了全WA，这究竟是道德的扭曲还是人性的沦丧!!!

#include<iostream>
#include<cmath>
#include<string.h>
using namespace std;
struct VILLAGE{
	double x,y;
}vill[28];
int n;
double D,dp[1048576][28],road[28][28];
double get_dist(int a,int b)
{
	return sqrt((vill[a].x-vill[b].x)*(vill[a].x-vill[b].x)+
				(vill[a].y-vill[b].y)*(vill[a].y-vill[b].y));
}
int main()
{
	int i,j,k,MST,x,y;
	double dist,ans;
	cin>>n>>D;
	MST=(1<<n);
	for(i=1;i<=n;i++)
		cin>>vill[i].x>>vill[i].y;
	for(i=0;i<=MST;i++)
		for(j=0;j<=n+1;j++)
			dp[i][j]=9999999;
	for(i=1;i<=n;i++)
	{
		for(j=1;j<=n;j++)
		{
			dist=get_dist(i,j);
			if(dist>D) dist=9999999;
			road[i][j]=dist;
		}
	}
	for(k=1;k<=n;k++)
		for(i=1;i<=n;i++)
			for(j=i+1;j<=n;j++)
				road[i][j]=min(road[i][j],road[i][k]+road[k][j]);
	dp[1][1]=0;
	for(i=1;i<MST;i++)
	{
		for(j=1;j<=n;j++)
		{
			if(((1<<(j-1))&i)==0) continue;
			x=i-(1<<(j-1));
			for(k=1;k<=n;k++)
			{
				if(((1<<(k-1))&x)==0) continue;
				dp[i][j]=min(dp[i][j],dp[x][k]+road[j][k]);
			}
		}
	}
	ans=dp[MST-1][1];
	for(i=2;i<=n;i++)
	{
		ans=min(ans,dp[MST-1][i]+road[1][i]);
	}
	printf("%.2lf",ans);
	return 0;
}