Compilare: user.cpp: In function ‘void bfs_1()’: user.cpp:50:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v[k].size(); ++i) ^ user.cpp: In function ‘void bfs_2()’: user.cpp:68:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v[k].size(); ++i) ^