Compilare: user.cpp: In function ‘std::vector<PTX> make_hull(std::vector<PTX>)’: user.cpp:47:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<ptr.size(); ++i) { ^ user.cpp:55:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<ue.size(); ++i) ^ user.cpp: In function ‘int bfs(int)’: user.cpp:148:1: warning: control reaches end of non-void function [-Wreturn-type] } ^