Compilare: user.cpp: In function ‘int main()’: user.cpp:39:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s1.size(); i++) ^ user.cpp:41:24: warning: array subscript has type ‘char’ [-Wchar-subscripts] positions[s1[i]].push(i); ^ user.cpp:46:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s2.size(); i++) { ^ user.cpp:49:25: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (positions[ch].empty()) { ^ user.cpp:54:36: warning: array subscript has type ‘char’ [-Wchar-subscripts] int position = positions[ch].front(); ^ user.cpp:55:21: warning: array subscript has type ‘char’ [-Wchar-subscripts] positions[ch].pop(); ^