/in/foo.cc: In function 'void addEdge(int, int)':
/in/foo.cc:18:5: error: reference to 'next' is ambiguous
     next[tot] = head[x]; //当前边和head[x] 链接 此时head[x]：记录x作为终点的边是谁
     ^~~~
/in/foo.cc:10:14: note: candidates are: int next [2004]
 int adj[mm], next[mm];
              ^~~~
In file included from /usr/include/c++/7/bits/stl_algobase.h:66:0,
                 from /usr/include/c++/7/bits/char_traits.h:39,
                 from /usr/include/c++/7/ios:40,
                 from /usr/include/c++/7/ostream:38,
                 from /usr/include/c++/7/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/7/bits/stl_iterator_base_funcs.h:208:5: note:                 template<class _ForwardIterator> _ForwardIterator std::next(_ForwardIterator, typename std::iterator_traits<_Iter>::difference_type)
     next(_ForwardIterator __x, typename
     ^~~~
/in/foo.cc: In function 'bool dfs(int)':
/in/foo.cc:34:16: error: reference to 'next' is ambiguous
         temp = next[temp]; //下条边的终点
                ^~~~
/in/foo.cc:10:14: note: candidates are: int next [2004]
 int adj[mm], next[mm];
              ^~~~
In file included from /usr/include/c++/7/bits/stl_algobase.h:66:0,
                 from /usr/include/c++/7/bits/char_traits.h:39,
                 from /usr/include/c++/7/ios:40,
                 from /usr/include/c++/7/ostream:38,
                 from /usr/include/c++/7/iostream:39,
                 from /in/foo.cc:1:
/usr/include/c++/7/bits/stl_iterator_base_funcs.h:208:5: note:                 template<class _ForwardIterator> _ForwardIterator std::next(_ForwardIterator, typename std::iterator_traits<_Iter>::difference_type)
     next(_ForwardIterator __x, typename
     ^~~~