Compilare: user.cpp: In function ‘void DFS(int, std::vector<std::vector<int> >&, std::vector<bool>&)’: user.cpp:8:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < nodes[i].size(); j++) { ^ user.cpp: In function ‘int main()’: user.cpp:16:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dfs.in", "r", stdin); ^ user.cpp:17:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dfs.out", "w", stdout); ^