Compilare: main.cpp: In member function 'void Trie::insert(std::__cxx11::string&)': main.cpp:41:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i <= s.size(); ++i) { ~~^~~~~~~~~~~ main.cpp:43:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (s.size() == i) { ~~~~~~~~~^~~~ main.cpp:49:33: warning: array subscript has type 'char' [-Wchar-subscripts] if (node->children[c] == NULL) { ^ main.cpp:50:33: warning: array subscript has type 'char' [-Wchar-subscripts] node->children[c] = new Trie(); ^ main.cpp:53:36: warning: array subscript has type 'char' [-Wchar-subscripts] node = node->children[c]; ^ main.cpp: In member function 'bool Trie::contains(std::__cxx11::string&)': main.cpp:60:27: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i <= s.size(); ++i) { ~~^~~~~~~~~~~ main.cpp:61:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (s.size() == i) { ~~~~~~~~~^~~~ main.cpp:67:33: warning: array subscript has type 'char' [-Wchar-subscripts] if (node->children[c] == NULL) { ^ main.cpp:71:36: warning: array subscript has type 'char' [-Wchar-subscripts] node = node->children[c]; ^