The first round had lots of hard math/probability problems. Then, the next round was a CodePen challenge where you had to solve the problem live in front of them. I initially tried to do it in SML because that's the only functional programming language we learned in school, and I know Jane Street likes that. However, that was a big flop and completely unnecessary, as I just ended up asking to do it in Python.

How to reduce the addresses in various ports.

For example, if you have ports = {"a": "12.x.y.3", "x": "4", "y": "x.x"}, you first replace y='x.x' with y='4.4' since x=4.

Then, you replace a='12.x.y.3' with a='12.4.4.3'.