Need help in reviewing a Go challenge for SSE role

I tried solving the above challenge, and the code that I came up with within an hour looked something like this, I missed few things and I know about that. But what and how can I improve? Especially the feedback that I got for the Part 2 is something I don’t understand. He said the solution isn’t correct( the implementation isn’t correct ).

Things I missed:

table tests
I wasn’t able to structure code and so I did a hack, made an executable and then simply change the package names so that the test could run.

You only had one go-routine in Part B.

Yeah. And for some reason, I am not able to understand what to do next.