初用NOI LINUX求助

#include<bits/stdc++.h>
#define d(x) cerr<<#x<<"="<<x<<endl
#define ll long long
#define sparkle cerr<<"happyhappyhappy"<<endl
using namespace std;
const int maxn=200005;
const int mod=1000000007;
ll dp[maxn];
struct Edge
{
	ll v;
	bool istrue;
};
vector<Edge> q[maxn];
inline void dfs1(ll now,ll from)
{
    for(auto v:q[now])
    { 
        if (v.v==from)
        {
            continue;
        }
        dfs1(v.v,now);
        dp[now]+=dp[v.v]+v.istrue;
    }
}
inline void dfs2(ll now,ll from)
{
    for(auto v:q[now])
    {
    	if (v.v==from)
        {
            continue;
        }
        dp[v.v]=dp[now]+(1-2*v.istrue);
        dfs2(v.v,now);
    }
}
inline void solve()
{
	ll n,u,v;
	cin>>n;
	for(int i=1;i<n;i++)
	{
		cin>>u>>v;
		q[u].push_back({v,0});
		q[v].push_back({u,1});
	}
	for(int i=1;i<=n;i++)
		dp[i]=0;
	dfs1(1,0);
	dfs2(1,0);
	ll minn=LLONG_MAX;
	for(int i=1;i<=n;i++)
	{
		minn=min(minn,dp[i]);
	}
	cout<<minn<<endl;
	for(int i=1;i<=n;i++)
	{
		if(dp[i]==minn)
			cout<<i<<" ";
	}
	cout<<endl;
}

int main()
{
	freopen("data.in","r",stdin);
	freopen("data.out","w",stdout);
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	int _;
	_=1;
	while(_--)
	{
		solve();
	}
	return 0;
}