代码：
// Created by CAD on 2019/11/21.
#include <bits/stdc++.h>
using namespace std;
const int maxn=1e5+5;
int vis[maxn],bj[maxn];
vector<int> v[maxn];
int ans[maxn];
int main()
{
ios::sync_with_stdio(false);
cin.tie(0);
int n;cin>>n;
for(int i=1;i<=n-2;++i)
{
int a[4];
for(int j=1; j<=3; ++j)
cin>>a[j],bj[a[j]]++;
for(int j=1; j<=3; ++j)
for(int k=1;k<=3;++k)
if(j!=k)
v[a[j]].push_back(a[k]);
}
for(int i=1;i<=n;++i)
if(bj[i]==1) ans[1]=i;
ans[2]=v[ans[1]][0],ans[3]=v[ans[1]][1];
if(bj[ans[2]]==3) swap(ans[2],ans[3]);
cout<<ans[1]<<" "<<ans[2];
vis[ans[1]]=vis[ans[2]]=1;
for(int i=1;i<=n-2;++i)
{
for(auto k:v[ans[1]]) if(!vis[k]) ans[3]=k;
cout<<" "<<ans[3];
vis[ans[3]]=1;
ans[1]=ans[2],ans[2]=ans[3];
}
cout<<endl;
return 0;
}