Was called about 3 minutes late. Interviewer was nearly unintelligible, and I knew regardless of the outcome that this was going to be a less than ideal interview setting. I'd like to add my own input here after researching the question: the solution I found was working and optimal, though it took me roughly 20 minutes to solve the problem since 5-6 were spent trying to understand what type of English was being spoken through the phone. The question was fair but difficult, and I missed a few boundary cases to be sure. In retrospect and for all those who may think of applying: bring your perfectionist game because mistakes and misinterpretations will not be tolerated no matter who's fault it is. In this sense, I don't believe this company was a right fit for me.