Contacted by a recruiter, I had an initial phone interview and then an onsite at the Seattle office. The interviewers were mainly new hires and not very senior people from the industry. It seemed to me that the interviewers were just trying to show off. I am not afraid of complex coding questions, but the interviewers spent a lot of time in "crap-talking," which resulted in only 20-25 minutes to finish coding.

1. Write a program to print all paths in a binary tree where the path sum is equal to a given number. This was asked in a telephonic screening.

2. How will you serialize and de-serialize a binary tree?

3. Find a median for a stream of numbers. Now, design a service that has this API to perform these operations. You have multiple streams now.

4. Given a start string "ball", an end string "John", and a dictionary that contains some words, find if you can convert "ball" to "John" by changing one character at a time, using the words from the dictionary. How will you design a large-scale service to do the same?