Compilare: user.cpp: In function ‘int main()’: user.cpp:42:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<costs.size() && tree_edges.size()<n-1;i++) ^ user.cpp:42:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<costs.size() && tree_edges.size()<n-1;i++) ^ user.cpp:66:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<tree_edges.size();i++) ^