Compilare: user.cpp: In function ‘void insert(ptrie, int, int)’: user.cpp:45:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i==c.size()) ^ user.cpp: In function ‘void read()’: user.cpp:105:27: 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:125:43: 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); ^ user.cpp:126:45: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ahocorasick.out", "wt", stdout); ^