I applied online and was contacted 1-2 weeks afterward.

After two phone interviews, I was invited for an on-site interview in Sunnyvale, CA, at the beginning of March. The interview consisted of four technical interviews and one Engineering Director lunch interview.

The overall technical interview process was as expected, with the exception of one disagreement:

One question asked to determine the median of a stream of numbers at any given moment. I stated that, in the case of an even amount of numbers, the median is the average of the middle pair of numbers after they are rearranged in ascending order. The interviewer instantly denied this logic and became angry, stating that: "When there are an even amount of numbers, the median can be either the lower or the higher element!"

Although this was a small disagreement, it made me feel there is no room for discussion in the "glorious halls" of Yahoo!.

Also, be very aware of the lunch with the Engineering Director. In the emails, it was stated that the lunch would be a strictly casual, non-interview process. However, the Engineering Director asked technical questions, including algorithms and data structures, and behavioral/personality questions like: "What do you want to do in 3 years?", "Why do you want to join Mail/Antispam?", "Do you like machine learning?", "Tell me some machine learning techniques.", "Where did you come from (which country)?", and "At what age?" So, be prepared.

Lastly and most importantly, it has been almost three months since the beginning of March, and they still haven't reimbursed me for money spent on the interview. I was in Sunnyvale, California, for three days and spent roughly $200-$300 out of my own pocket for travel, food, and parking. I have been emailing them every week regarding the reimbursement, and all I get from HR is that they will look into it. It's been almost three months, and all they can do is "look into it." I am only a student, and it would be really nice to see that money again. T___T

Be prepared to spend money out of your own pocket when you are called by Yahoo! for an interview.

Determine the number of bits of a given number in O(1) time.