Compilare: user.cpp: In function ‘void ahocorasick(trie_node_t*, std::string&)’: user.cpp:71:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); ++i) { ^ user.cpp: In function ‘int main()’: user.cpp:102:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ahocorasick.in", "rt", stdin); ^