Compilare: main.cpp: In function 'int _delete(int, Node*, std::string&)': main.cpp:34:10: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare] 34 | if(i == s.size()) | ~~^~~~~~~~~~~ main.cpp: In function 'int _prefix(std::string&)': main.cpp:61:12: warning: unused variable 'lg' [-Wunused-variable] 61 | int i, lg = 0, n = s.size(); | ^~ main.cpp: In function 'int main()': main.cpp:76:20: warning: unused variable 'start' [-Wunused-variable] 76 | struct timeval start, stop; | ^~~~~ main.cpp:76:27: warning: unused variable 'stop' [-Wunused-variable] 76 | struct timeval start, stop; | ^~~~