Compilare: user.cpp: In member function ‘int Trie::length_com_pref(int, int*, int)’: user.cpp:66:60: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0;i < vec[mid][s[id][mid] - 'a'].size();++i) ^ user.cpp:72:72: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (k = 0; k < vec[mid][s[id][mid] - 'a'][i]->vec[g[j] % 23].size();++k) ^ user.cpp:75:65: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k == vec[mid][s[id][mid] - 'a'][i]->vec[g[j] % 23].size()) ^ user.cpp:59:11: warning: unused variable ‘q’ [-Wunused-variable] Node *q = t; ^ user.cpp: In function ‘int main()’: user.cpp:111:16: warning: unused variable ‘f’ [-Wunused-variable] int e, f; ^ user.cpp:99:9: warning: unused variable ‘op’ [-Wunused-variable] int op; ^