If you don't know, FooBar with Google is a secret challenge used by Google to (sometimes) hire engineers. Since Google knows all, they invite developers that match a certain profile based on their search history and browser fingerprint (I'd imagine, at least.) It's sort of secret, but well-know--and great fun. Here's some more background about it.
The challenge structure is as follows: for each challenge, you are given a list of constraints and test cases to be in compliance with. After receipt of the challenge, you have a certain amount of time to successfully test your code, in either Java or Python, against the test cases and hidden tests cases before submission. The challenges test algorithm, data structure, and mathematics knowledge, and range from as hard as the hardest interview questions you'd ever be asked to month-long research marathons.
I recently got the opportunity to participate in its latest iteration, and as someone who doesn't consider herself one for code golf, Leetcode, and other code challenges I thought I'd blog about it from a DevOps/SRE perspective. You can find that blog series here