Compilare: user.cpp: In function ‘int DFS(int)’: user.cpp:21:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < v[u].size(); ++i){ ^ user.cpp:28:1: warning: no return statement in function returning non-void [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:39:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0; i < root.size(); ++i){ ^ user.cpp:46:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(y < sol[x].size() + 1 && !sol[x].empty()) g << sol[x][y-1] << '\n'; ^