Just sharing my experience of my spontaneous interview with Facebook. I'm not good at writing these but here you go :)

- I was working as an Android dev and didn't have much knowledge in algorithms nor competitive programming, never ever interviewed with big companies.
- a random day on LinkedIn, a recruiter from Facebook contacted me
- I ignored it for few week because I thought it's so out of my league, then somehow, out of blue, I had a thought of giving it a try, so I did
- passed first round
- start studying algorithms a little for phone interview in 3 weeks
- recklessly took the phone interview
- passed
- start studying intensively (while working fulltime) for the on-site interview in 2 months
- almost got the job, they gave me one more chance by a followed up interview
- messed up the last chance real bad
- failed!!!
- Initially I just wanted to give it a try, but the fact that I failed at very very last chance, frankly, bothers me a bit. Maybe I will interview with FB or big companies if I have chance later, but I know for sure that the studying had made me a much better dev. All the code I write now is much more efficient (I think), I can and not anymore afraid of reading complicated code.
- Overall, it does takes a lot of time (~4 months studying while working fulltime), but also benefits myself a lot though I didn't get the job, so basically, good experience, but better if I got the job 😁

Oops, wanted to write a few lines and it's a long post already.. I should stop here :D