The HackerRank challenge was followed by a phone interview. They are understandably, or try to be, obsessed with file-related LeetCode-style questions.

The coding test consisted of implementing shared text editor features, such as highlighting text and copy-pasting selections from the clipboard. I cleared the coding interview, or was deemed worthy of a phone interview as per the recruiter's email (not kidding).

The interviewer was an inexperienced engineer who asked me to implement a question related to files again! The interviewer asked a follow-up after I implemented the solution, which I could not think of on the spot. There was also the weird presence of a ghost who was shadowing the interview and who did not reply when I said hello after the interviewer mentioned the ghost interviewer. I got rejected with feedback that my coding wasn't where they expected it to be. They are clearly riding high on the surge in the candidate pool due to the role being remote. Overall, a silly screening process.

Given a directory path as input, which contains directories and files recursively, write a function that returns a list of lists of files that are identical (i.e., have the same content and the same size).

As a follow-up, if we are given input file sizes, how can we prune the input file list that needs to be processed by the function?