Compilare: user.cpp: In function ‘std::map<int, int> dijkstra(Graph&, int)’: user.cpp:18:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (dist.size() < N) { ^ user.cpp: In function ‘int main()’: user.cpp:34:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("data.in", "r", stdin); ^ 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("data.out", "w", stdout); ^