HR scheduled a phone screening interview with one of the engineers. The interviewer asked about my current company, role, and day-to-day activities, and then briefed me about the role and team for which I was being interviewed. The interviewer then quickly moved on to the coding round. The question was to group anagrams from a given list of words. I quickly outlined my approach (hash tables) and started coding in Python. I was able to successfully execute the program with the desired output. The interviewer asked about the time complexity and corner/stress cases for the given problem. I was able to answer all questions related to the coding problem, and the interviewer looked convinced. A day later, HR emailed me, stating that she had received negative feedback from the interviewer and that they had decided not to pursue my application further. This entire episode baffles me to this day.

Given a list of words, group the anagrams.