The application process was divided into the following stages:

• Phone (CV screen)
• Technical interview (HackerRank, data structures)
• On-site interview

They invited me to London after the second stage. However, four days before my trip (they forgot about the time difference, calling me at 5 AM!), they asked for one more interview, which was planned for two days before my planned trip (actually a little more than one day, taking the flight departure into consideration).

The second interview (optimization, algorithms) was quite difficult and clearly intended to eliminate a candidate.

Pretty rough, but still very unprofessional. On top of that, the following morning, I received an email asking if they could call me. I responded within 60 seconds with a "yes, please call me." I waited 30 minutes for their call and eventually received an automatically generated message stating my application was no longer being processed. There was no feedback.

It's hard to plan your university deadlines, meetings, and assignments with such disorganization.

Q: Cannot say, but about the graph and optimizing the flow.