Compilare: user.cpp: In function 'std::vector<std::pair<char, char>, std::allocator<std::pair<char, char> > > modify(const std::vector<std::pair<char, char>, std::allocator<std::pair<char, char> > >&, char)': user.cpp:17: warning: array subscript has type 'char' user.cpp:17: warning: array subscript has type 'char' user.cpp:18: warning: array subscript has type 'char' user.cpp:18: warning: array subscript has type 'char' user.cpp:19: warning: array subscript has type 'char' user.cpp:19: warning: array subscript has type 'char' user.cpp:20: warning: array subscript has type 'char' user.cpp:20: warning: array subscript has type 'char' user.cpp: In function 'bool solve(const std::vector<std::pair<char, char>, std::allocator<std::pair<char, char> > >&)': user.cpp:34: warning: array subscript has type 'char' user.cpp:34: warning: array subscript has type 'char' user.cpp:35: warning: array subscript has type 'char' user.cpp:35: warning: array subscript has type 'char' user.cpp:36: warning: array subscript has type 'char' user.cpp:36: warning: array subscript has type 'char' user.cpp:37: warning: array subscript has type 'char' user.cpp:37: warning: array subscript has type 'char' user.cpp: In function 'int main()': user.cpp:103: warning: array subscript has type 'char' user.cpp:103: warning: array subscript has type 'char' user.cpp:104: warning: array subscript has type 'char' user.cpp:104: warning: array subscript has type 'char' user.cpp:105: warning: array subscript has type 'char' user.cpp:105: warning: array subscript has type 'char'