/in/foo.cc: In function 'void spfa()':
/in/foo.cc:27:31: error: reference to 'next' is ambiguous
for(int i=head[x];i;i=next[i])
^~~~
/in/foo.cc:10:19: note: candidates are: int next [300005]
int head[N],go[N],next[N],val[N];
^~~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:66:0,
from /usr/include/c++/6/algorithm:61,
from /in/foo.cc:2:
/usr/include/c++/6/bits/stl_iterator_base_funcs.h:205:5: note: template<class _ForwardIterator> _ForwardIterator std::next(_ForwardIterator, typename std::iterator_traits<_Iter>::difference_type)
next(_ForwardIterator __x, typename
^~~~
/in/foo.cc: In function 'void add(int, int, int)':
/in/foo.cc:61:5: error: reference to 'next' is ambiguous
next[tot]=head[x];
^~~~
/in/foo.cc:10:19: note: candidates are: int next [300005]
int head[N],go[N],next[N],val[N];
^~~~
In file included from /usr/include/c++/6/bits/stl_algobase.h:66:0,
from /usr/include/c++/6/algorithm:61,
from /in/foo.cc:2:
/usr/include/c++/6/bits/stl_iterator_base_funcs.h:205:5: note: template<class _ForwardIterator> _ForwardIterator std::next(_ForwardIterator, typename std::iterator_traits<_Iter>::difference_type)
next(_ForwardIterator __x, typename
^~~~