Compilare: user.cpp: In function ‘void dfs1(int)’: user.cpp:31:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( int i = 1 ; i <= a[x].size() ; i++ ) ^ user.cpp: In function ‘void dfs2(int)’: user.cpp:55:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( int i = 1; i <= a[x].size() ; i ++ ) ^