代码如下：

#include<iostream>
#include<cstring>
#include<algorithm>
#include<vector>
#include<stack>
using namespace std;
#define N 1005
#define reint register int
int n,num,visn,stan,dfn[N],lows[N],sta[N],fa[N],k,ans;
vector<int>g[N];
vector<int>h[N];
stack<int>s;//ghs:干好事 
struct Edge{
	int from;
	int to;
	int val;
}edge[N*N];
inline bool cmp(Edge a,Edge b)
{
	return a.val<b.val;
}
int finds(int x)
{
	if(x!=fa[x])fa[x]=finds(fa[x]);
	return fa[x];
} 
inline void unions(int x,int y)
{
	x=finds(x),y=finds(y);
	fa[x]=y;
}
void Tarjan(int u)
{
	dfn[u]=lows[u]=++visn;
	s.push(u);
	for(reint i=0;i<g[u].size();++i)
	{
		int v=g[u][i];
		if(!dfn[v])
		{
			Tarjan(v);
			lows[u]=min(lows[u],lows[v]);
		}
		else if(!sta[v])
		lows[u]=min(lows[u],dfn[v]);
	}
	if(dfn[u]==lows[u])
	{
		sta[u]=++stan;
		while(s.top()!=u)
		{
			sta[s.top()]=stan;
			s.pop();
		} 
		s.pop();
	}
}
inline void starts()
{
	memset(dfn,0,sizeof(dfn));
	memset(lows,0,sizeof(lows));
	memset(sta,0,sizeof(sta));
	for(reint i=1;i<=n;++i)fa[i]=i; 
}
int main()
{
	ios::sync_with_stdio(false);
	cin>>n;
	starts();
	for(reint i=1;i<=n;++i)
	{
		int x,y;
		cin>>x>>y;
		g[x].push_back(y);
		g[y].push_back(x);
	}
	for(reint i=1;i<=n;++i)
	if(!dfn[i])Tarjan(i);
	for(signed i=1;i<=n;++i)
	for(signed j=1;j<=n;++j)
	{
		int val;
		cin>>val;
		if(sta[i]==sta[j])continue;
		edge[++num].from=sta[i];
		edge[num].to=sta[j];
		edge[num].val=val;
	}
	sort(edge+1,edge+1+num,cmp);
	for(signed i=1;i<=num;++i)
	{
		int x=edge[i].from,y=edge[i].to;
		if(finds(x)!=finds(y))
		{
			unions(x,y);
			ans+=edge[i].val;
			++k;
			if(k==stan-1)break;
		}
	}
	cout<<ans*2<<'\n';
	return 0;
}

（悲