I had a phone screen with a recruiter and then a technical phone interview with an engineer.

Subsequently, I was invited for an onsite interview, where I completed five back-to-back whiteboard coding interviews, all with senior engineers.

I am still waiting for the final decision.

I'm under an NDA, so I cannot disclose the specific questions.

The questions I was asked were much more difficult than what my friends had and what people posted on websites like Glassdoor, LeetCode, or CareerCup.

They were about algorithms and data structures, but far from obvious.

One question tested my knowledge of some arcane number theory concepts, which I of course didn't know.

I would say the questions I had required much more than just the basic concepts found in a typical algorithms textbook.

I managed to solve them with the help of many hints from the interviewers, so I don't think I'll get the offer.

Honestly, if Google expects people to solve questions of that difficulty flawlessly and effortlessly, I can never meet that standard. There's no chance.