I interviewed there as an SRE many years ago (early-mid 2000's)
and I was asked about mathematical algorithms, whether I'd published any books in tech, and what open source I contributed to.
I would have needed to study for a year or more of math since I never studied math in college, and I wasn't just out of college. Even someone with a computer science degree, once they've been a professional for a few years, would need to crack open college textbooks again to pass a Google interview.
Unless they did math as a hobby, which I will refrain from commenting on at this time.
I got a job at Aflac on my first try. I was even offered my choice of jobs as I qualified for more than one position. I applied because my mother suggested it. It was outside of the field I desired to go into.
A coworker of mine spent 5 years applying and reapplying and trying to improve their qualifications until they finally got hired.
I don't see any reason to question the statement that GP invested 200 hours.
It isn't an exaggeration. In the same time span (2 months) I spent about 90 hours playing Oxygen Not Included and about 60 hours playing Darkest Dungeon. And that was me trying to play games less.
When I started I didn't know what dynamic programming meant and I didn't know how to implement a breadth first search. (I thought it required a priority queue). So a lot of time was spent reviewing things like N Queens and dijkstra's algorithm because I hadn't touched it since university.
In the end I spent too much time on things I never got asked and I should have been practicing on paper instead of a computer.
I would have needed to study for a year or more of math since I never studied math in college, and I wasn't just out of college. Even someone with a computer science degree, once they've been a professional for a few years, would need to crack open college textbooks again to pass a Google interview.
Unless they did math as a hobby, which I will refrain from commenting on at this time.