Compilare: user.cpp: In function ‘int main()’: user.cpp:32:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s1.size (); i++) { ^ user.cpp:33:16: warning: array subscript has type ‘char’ [-Wchar-subscripts] H[s1[i]].push_back (i + 1); ^ user.cpp:36:24: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (H[s2[i - 1]].empty ()) { ^ user.cpp:40:30: warning: array subscript has type ‘char’ [-Wchar-subscripts] int nod = H[s2[i - 1]].front (); ^ user.cpp:41:20: warning: array subscript has type ‘char’ [-Wchar-subscripts] H[s2[i - 1]].pop_front (); ^