I was called on time for a coding interview via coderpad.io. The initial conversation was brief because the main interviewer had joined Dropbox recently and basically had nothing to talk about regarding job experience, etc.

The problem statement was simple: "Find all duplicate files by content in your filesystem." However, the question was somewhat awkward via coderpad.io because it involved I/O. I didn't know what to expect from traversing a real filesystem via coderpad.io.

I have experience working with low-level filesystem design, so I tried to clarify the problem statement but didn't get much help (e.g., http://wiki.osdev.org/File_Systems).

To make things more confusing, the interviewer described the problem using a list of arrays that seemed like the input. As a matter of fact, that was the expected output. I realized this because after 20 minutes of working with it as input, he pasted the actual input as a tree.

I ran out of time because I was basically designing my own index from the input (or output) then doing a tree traversal.

Find all duplicate files by content in your filesystem.