I applied through an employee referral. The process took 1 week. I interviewed at Block (San Francisco, CA) in May 2014
Interview
Quick phone call followed by a coderpad-based interview done over Skype. The interview consists of the guy from Square giving you the problem statement, and I was expected to write a working solution - including test cases - which is compiled and run within coderpad. I had to do two of these because the first one was inconclusive.
The first problem I got was writing an arithmetic expression parser with only parentheses and the '+' sign. This was fairly straightforward. Then, he asked to parse a list of expressions instead of just one. Then, some expressions could reference others in the list (e.g. A3 + 1) which was as far as we got. I successfully wrote the code but I think he was displeased with my messy design as it was "patched through" on the initial design. Eventually the recruiter informed me that I need to do another coderpad session.
The second interview was much like the first. The problem this time was to write a class scheduler, where each class could have multiple time slots and we need to choose a combination of times so that we can take each class. I tried this time to focus on designing it properly in OO but it took so much time that I was only able to reach one evolution of the problem - return all possible arrangements instead of just the first. I haven't received an official response yet but I'm pretty sure I effed this one up as I was probably expected to reach at least step 3 or 4. Oh well..
Interview questions [1]
Question 1
Overall, both problems were non-trivial and the requirement of writing working code + tests in a one hour interview makes this probably the toughest interview I've done to date. If you're doing this, make sure you are able to solve the above problems quickly and properly OO. Use python (or similar) to save some time on list comprehension. Good luck!
Inital take home, followed by extension interview, followed by a coding challenge, followed by system design interview.
The whole process took 3 months!
The interviewers are usually really nice and want you to do your best.
The interviewer was nice, and he is friendly and willing to give hint, the question has 2 follow-ups, it was hard to complete in time. The question was not a typical LeetCode
Phone screen and then a full day of interviews. 3 pair programming challenges, a system design review and a prior experience interview. There was also an onsite lunch with a person from the company.
Interview questions [1]
Question 1
To design a hotel booking system. Pick any part (backend, frontend, database, api etc) and deepdive into that, explaining the decisions along the way.