Google Interview Questions & Reviews

Interviewed Apr 2011 in Montreal, QC (Canada) (took a day)

This position was advertised to university students; applications were handled through the school. The interview itself took place on campus, and consisted of only one interviewer.

I was asked a few basic questions about Java (difference between abstract classes and interfaces, whether multiple inheritance is possible, why might the designers of Java not have allowed multiple inheritance). I got the sense that the interviewer felt good about my Java skills early on, and skipped over to the next part of the interview.

Next, I was asked to write a Java program that reverses a 2D bitmap (i.e. 2D integer array) that is represented as a 1D array. I felt that I got off to a good start, but eventually started to verify by trial and error that I was indexing the 1D array correctly in my algorithm. The interviewer commented (respectfully) that perhaps I should try to think it through logically, rather than trying to verify my formula through trial and error. He helped me move along, and wrote down my code into his notebook when I was done (I assume, to look at it more closely later on).

I was asked one final question: if you have a network of computers, and a massive file (e.g. tens of gigabytes) on one of the machines, how would you efficiently copy the file to all of the machines on the network. I asked him what the bottleneck is and he said that it is the network cards on the machines. I suggested a bittorrent-style architecture in which one machine starts to copy the part of the file that it has already received, before having the entire file. He asked me what the time complexity was of this solution and I told him that it would be linear with regards to the size of the file.

He then asked me if I had any questions and was good about providing me with detailed answers. Other than tripping over the 2D bitmap question a bit, I felt that the interview went well. He told me that I would likely hear back from them within two weeks, but I never did. I assumed that this was due to my school acting as the intermediary, but upon contacting the school weeks later, they said that they were never contacted.