Compilare: user.cpp: In function ‘void dijkstra(int)’: user.cpp:20:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v[1].size(); i++) s.insert(make_pair(v[1][i].second,v[1][i].first)); ~^~~~~~~~~~~~ user.cpp:27:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<v[nod].size(); i++) ~^~~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:36:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dijkstra.in","r",stdin); ^ user.cpp:37:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("dijkstra.out","w",stdout); ^