I applied online. The process took 3 weeks. I interviewed at Block (San Francisco, CA) in Oct 2013
Interview
I submitted my resume to my university's career website, after which I received an email to complete a coding challenge online. This was used to determine whether I got an on-campus interview. There were two questions, both of which I put below. I finished the first and got halfway through the second one.
After that I got the on-campus interview, which was pair-coding style. We implemented a least-recently-used cache in Java. It was fun, and I was able to Google syntax I didn't know, and we ended up getting it to run.
A bit later, I got an email to set up an on-site interview at Square in SF. This consisted of breakfast, three pair coding interviews, lunch, a few talks, coffee at Sightglass, and then that was it.
The three questions I got were:
1. find all prime numbers under a given number
2. Fraud detection: if two merchants have swiped the same card, they are part of the same component. Find the size of the component.
3. parse TVL bytes and return cardholder name.
I struggled with the last one in particular. I was notified of no offer after a week.
Interview questions [2]
Question 1
input: coefficients line (a’s), lines of values from transactions (x’s)
y = a0 + a1*x1 + a2*x2 + ... + aN*xN
y <= 0 not fraud, y > 0 suspect fraud
output fraud/not fraud for each line of N lines
input: two numbers, N and M, which define an NxM grid
start at top left corner of grid (1,1):
- step forward
- turn right
- if space in front of you is out of board or you already walked on it, turn right
keep going until you can’t walk anymore
output is number of steps you take before stopping.
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.
