View Compilation Error

0_0_23940354_5458.cpp: In function 'int get_hash(std::string)':
0_0_23940354_5458.cpp:41:14: error: reference to 'hash' is ambiguous
         s+=k*hash[i];
              ^
0_0_23940354_5458.cpp:13:5: note: candidates are: int hash [9]
 int hash[9]={1,1,2,6,24,120,720,5040,40320};
     ^
In file included from GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/basic_string.h:3068:0,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/string:52,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/locale_classes.h:40,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/ios_base.h:41,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/ios:42,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/ostream:38,
                 from GCC4.9.2/x86_64-w64-mingw32/include/c++/iostream:39,
                 from 0_0_23940354_5458.cpp:1:
GCC4.9.2/x86_64-w64-mingw32/include/c++/bits/functional_hash.h:58:12: note:                 template<class _Tp> struct std::hash
     struct hash;
            ^