Two phone interviews were conducted. Both individuals were pleasant, though the technical interviewer was somewhat awkward.

The first interview was with the recruiter to discuss available opportunities and to determine potential role compatibility.

The second interview was an hour-long technical screen, which primarily involved solving two technical problems: one was easy, and the other was difficult.

A few days later, the recruiter contacted me to inform me that while I had performed well on the technical problems, upon reviewing my resume, they concluded there were no compatible open positions. They suggested reapplying in a few months to explore future openings.

You are given a binary tree and pointers to two nodes in the tree. Describe the fastest algorithm you can come up with to determine the closest common ancestor.

You are writing an application that receives a stream of individual items of data. The stream may be very long or very short, but you have no way of knowing how long it is (i.e., there's no trick to figuring out the size of the stream of data). How would you go about choosing m items such that any subset of m items was equally likely? (Not an even distribution of values, but just that any m items are equally likely to be chosen). For example, m=1000, and the number of items in the stream, n, may be 1000, or 10000, or 100000000, or much, much larger; there is no way to know how many.