Compilare: user.cpp: In function ‘void dfs(int, int, long long int)’: user.cpp:29:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < gf[node].size(); ++i) { ~~^~~~~~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:68:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("huffman.in", "r", stdin); ^ user.cpp:69:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("huffman.out", "w", stdout); ^