Compilare: user.cpp: In member function 'void trie::insert(std::string)': user.cpp:29: warning: comparison between signed and unsigned integer expressions user.cpp: In member function 'void trie::remove(std::string)': user.cpp:40: warning: comparison between signed and unsigned integer expressions user.cpp:47: warning: comparison between signed and unsigned integer expressions user.cpp:53: warning: comparison between signed and unsigned integer expressions user.cpp: In member function 'trie::trie_node* trie::find(std::string)': user.cpp:58: warning: comparison between signed and unsigned integer expressions user.cpp: In member function 'int trie::lcp(std::string)': user.cpp:67: warning: comparison between signed and unsigned integer expressions