Compilare: user.cpp: In member function 'trie& trie::operator+=(std::string)': user.cpp:42: warning: comparison between signed and unsigned integer expressions user.cpp: In member function 'void trie::build_euler()': user.cpp:75: warning: comparison between signed and unsigned integer expressions user.cpp:78: warning: comparison between signed and unsigned integer expressions user.cpp:79: warning: comparison between signed and unsigned integer expressions user.cpp: In member function 'int trie::LCA(int, int)': user.cpp:89: warning: operation on 'x' may be undefined