The question was easy but their interview format was very unreasonable. They called me on the phone and expected me to solve a relatively simple geometric problem on a skype screenshare within 1 hour. The fact that another person was evaluating my thought process and every alteration to the code made nervous and I completed with 3/4 cases complete. I was told the test was for measuring my algebraic problem solving skills. To have such deep oversight over someone's problem solving process is intrusive and unnerving.
Given the job requirement was for UI development and did not include such problems or processes and it felt like a surprise college exam. It wasn't clear if they were testing for working under pressure. Unless they revise their process, they will miss out on a lot of talent with different thinking styles and pace.
After about a week, I sent a follow up email and it was implied that I did not qualify.