Compilare: user.cpp: In function ‘int mex(std::vector<int>)’: user.cpp:17:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < L.size(); i ++) ^ user.cpp: In function ‘void DFS(int)’: user.cpp:33:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < L[node].size(); i ++) ^ user.cpp: In function ‘int mex(std::vector<int>)’: user.cpp:29:1: warning: control reaches end of non-void function [-Wreturn-type] } ^