UnExisted or Wrong QQ Group Number

[Oyyko]

At this page https://learn-sys.github.io/cn/csapp/ , It mentioned that the qq group number is 683966907. However, it is not a usable qq group number since when I search it on QQ, I got "No results".
A possible reason is that the Group Holder haven't set the group to be "findable through Group Number"

[mjc0608]

The number should be correct. I'm working with the group owner to resolve this issue.
Thanks for the message.

[mjc0608]

For now, please add the group 643874182, and ask people there to forward you to the csapp group.

[mjc0608]

I uploaded a QR code. Could you please have a try? If it works, please close this issue.

[Oyyko]

The QR Code is awesome. Thanks!