foo.cpp: In function 'int try_to_insert(int)':
foo.cpp:27:10: error: reference to 'hash' is ambiguous
  int h = hash(st[s]);
          ^~~~
foo.cpp:19:5: note: candidates are: int hash(int (&)[9])
 int hash(State& s){
     ^~~~
In file included from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/bits/basic_string.h:5628:0,
                 from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/string:52,
                 from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/bits/locale_classes.h:40,
                 from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/bits/ios_base.h:41,
                 from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/ios:42,
                 from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/ostream:38,
                 from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/iostream:39,
                 from foo.cpp:1:
C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/bits/functional_hash.h:58:12: note:                 template<class _Tp> struct std::hash
     struct hash;
            ^~~~
foo.cpp:32:7: error: reference to 'next' is ambiguous
   u = next[u];
       ^~~~
foo.cpp:16:21: note: candidates are: int next [1000000]
 int head[hashsize], next[MaxState];
                     ^~~~
In file included from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/bits/stl_algobase.h:66:0,
                 from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/bits/char_traits.h:39,
                 from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/ios:40,
                 from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/ostream:38,
                 from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/iostream:39,
                 from foo.cpp:1:
C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/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
     ^~~~
foo.cpp:34:2: error: reference to 'next' is ambiguous
  next[s] = head[h];
  ^~~~
foo.cpp:16:21: note: candidates are: int next [1000000]
 int head[hashsize], next[MaxState];
                     ^~~~
In file included from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/bits/stl_algobase.h:66:0,
                 from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/bits/char_traits.h:39,
                 from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/ios:40,
                 from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/ostream:38,
                 from C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/iostream:39,
                 from foo.cpp:1:
C:/MinGW32/lib/gcc/i686-w64-mingw32/6.3.0/include/c++/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
     ^~~~