Compilare: main.cpp: In member function 'void Trie::insert(std::__cxx11::string&, int)': main.cpp:39:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k >= s.size()) { ~~^~~~~~~~~~~ main.cpp:46:23: warning: array subscript has type 'char' [-Wchar-subscripts] if (children[c] == NULL) { ^ main.cpp:47:23: warning: array subscript has type 'char' [-Wchar-subscripts] children[c] = new Trie(); ^ main.cpp:51:19: warning: array subscript has type 'char' [-Wchar-subscripts] children[c]->insert(s, k + 1); ^ main.cpp: In member function 'void Trie::remove(std::__cxx11::string&, int, bool&)': main.cpp:55:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k >= s.size()) { ~~^~~~~~~~~~~ main.cpp:63:23: warning: array subscript has type 'char' [-Wchar-subscripts] if (children[c] == NULL) { ^ main.cpp:67:23: warning: array subscript has type 'char' [-Wchar-subscripts] if (children[c]->isEmptyNode()) { ^ main.cpp:71:19: warning: array subscript has type 'char' [-Wchar-subscripts] children[c]->remove(s, k + 1, didRemove); ^ main.cpp: In member function 'int Trie::count(std::__cxx11::string&, int)': main.cpp:78:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k == s.size()) { ~~^~~~~~~~~~~ main.cpp:84:23: warning: array subscript has type 'char' [-Wchar-subscripts] if (children[c] == NULL) { ^ main.cpp:88:26: warning: array subscript has type 'char' [-Wchar-subscripts] return children[c]->count(s, k + 1); ^ main.cpp: In member function 'int Trie::longestPrefix(std::__cxx11::string&, int)': main.cpp:95:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k == s.size() || children[c] == NULL) { ~~^~~~~~~~~~~ main.cpp:95:40: warning: array subscript has type 'char' [-Wchar-subscripts] if (k == s.size() || children[c] == NULL) { ^ main.cpp:99:23: warning: array subscript has type 'char' [-Wchar-subscripts] if (children[c]->isEmptyNode()) { ^ main.cpp:103:26: warning: array subscript has type 'char' [-Wchar-subscripts] return children[c]->longestPrefix(s, k + 1); ^