Compilare: main.cpp: In member function 'void Trie::insert(std::__cxx11::string&, int)': main.cpp:32:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k == s.size()) { ~~^~~~~~~~~~~ main.cpp:42:16: warning: array subscript has type 'char' [-Wchar-subscripts] if (m[c] == NULL) { ^ main.cpp:43:16: warning: array subscript has type 'char' [-Wchar-subscripts] m[c] = new Trie(); ^ main.cpp:46:12: warning: array subscript has type 'char' [-Wchar-subscripts] m[c]->insert(s, k + 1); ^