Language: C++

#include <cstdio>
#include <algorithm>

using namespace std;

int edge[300000],next[300000],first[300000];
int c1[300000],c2[300000],d1[300000],d2[300000],e[300000],h[300000];
int i,j,k,n,p,t,t1,t2,x,y,sum_edge;

inline void addedge(int x,int y)
{
	sum_edge++,edge[sum_edge]=y,next[sum_edge]=first[x],first[x]=sum_edge; 
	return;
}

int main()
{
	scanf("%d",&n);
	for (i=1;i<n;i++)
	{
		scanf("%d%d",&x,&y);
		addedge(x,y),addedge(y,x);
	}
	for (i=1;i<=n;i++)
		for (j=first[i];j!=0;j=next[j])
			if (next[first[edge[j]]])
				if (! d1[i])
					d1[i]=edge[j];
				else
					if (! d2[i])
						d2[i]=edge[j];
					else
						return puts("-1"),0;
			else
				e[i]++,h[i]=edge[j];
	for (i=1;i<=n;i++)
		if (! d2[i])
		{
			t=i;
			if (e[i])
				d2[i]=h[i],d1[h[i]]=i,e[i]--,t=h[i];
			if (! t1)
				t1=t;
			else
				t2=t;
		}
	for (k=0,p=0,i=t1;i!=t2;)
	{
		k++,c1[k]=e[i]+1;
		if (d1[i]==p)
			p=i,i=d2[i];
		else
			p=i,i=d1[i];
	}
	k++,c1[k]=e[i]+1;
	swap(t1,t2);
	for (k=0,p=0,i=t1;i!=t2;)
	{
		k++,c2[k]=e[i]+1;
		if (d1[i]==p)
			p=i,i=d2[i];
		else
			p=i,i=d1[i];
	}
	k++,c2[k]=e[i]+1;
	t1=1,t2=0;
	for (i=1;i<=k;i++)
	{
		if (c1[i]<c2[i])
		{
			t1=1,t2=0;
			break;
		}
		if (c2[i]<c1[i])
		{
			t1=0,t2=1;
			break;
		}
	}
	t=0;
	for (i=1;i<=k;i++)
		if (t1)
		{
			for (j=2;j<=c1[i];j++)
				printf("%d ",t+j);
			printf("%d ",t+1);
			t=t+c1[i];
		}
		else
		{
			for (j=2;j<=c2[i];j++)
				printf("%d ",t+j);
			printf("%d ",t+1);
			t=t+c2[i];
		}
	return 0;
}

Compiler output:
a.cc: In function 'void addedge(int, int)':
a.cc:12:37: error: reference to 'next' is ambiguous
   12 |         sum_edge++,edge[sum_edge]=y,next[sum_edge]=first[x],first[x]=sum_edge;
      |                                     ^~~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:66,
                 from /usr/include/c++/14/algorithm:60,
                 from a.cc:2:
/usr/include/c++/14/bits/stl_iterator_base_funcs.h:232:5: note: candidates are: 'template<class _InputIterator> constexpr _InputIterator std::next(_InputIterator, typename iterator_traits<_Iter>::difference_type)'
  232 |     next(_InputIterator __x, typename
      |     ^~~~
a.cc:6:18: note:                 'int next [300000]'
    6 | int edge[300000],next[300000],first[300000];
      |                  ^~~~
a.cc: In function 'int main()':
a.cc:25:40: error: reference to 'next' is ambiguous
   25 |                 for (j=first[i];j!=0;j=next[j])
      |                                        ^~~~
/usr/include/c++/14/bits/stl_iterator_base_funcs.h:232:5: note: candidates are: 'template<class _InputIterator> constexpr _InputIterator std::next(_InputIterator, typename iterator_traits<_Iter>::difference_type)'
  232 |     next(_InputIterator __x, typename
      |     ^~~~
a.cc:6:18: note:                 'int next [300000]'
    6 | int edge[300000],next[300000],first[300000];
      |                  ^~~~
a.cc:26:29: error: reference to 'next' is ambiguous
   26 |                         if (next[first[edge[j]]])
      |                             ^~~~
/usr/include/c++/14/bits/stl_iterator_base_funcs.h:232:5: note: candidates are: 'template<class _InputIterator> constexpr _InputIterator std::next(_InputIterator, typename iterator_traits<_Iter>::difference_type)'
  232 |     next(_InputIterator __x, typename
      |     ^~~~
a.cc:6:18: note:                 'int next [300000]'
    6 | int edge[300000],next[300000],first[300000];
      |                  ^~~~