Compilare: user.cpp: In constructor ‘TopoSort::TopoSort(std::vector<std::vector<int> >&)’: user.cpp:9:10: warning: ‘TopoSort::s_ix’ will be initialized after [-Wreorder] int V, s_ix; ^ user.cpp:7:15: warning: ‘std::vector<int> TopoSort::sorted’ [-Wreorder] vector<int> sorted; ^ user.cpp:11:3: warning: when initialized here [-Wreorder] TopoSort(vector< vector<int> >& edges) : ^ user.cpp: In function ‘int main()’: user.cpp:35:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortaret.in", "r", stdin); ^ user.cpp:36:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("sortaret.out", "w", stdout); ^ user.cpp:38:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:42:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^