OptionMetrics Junior Software Engineer interview questions

Applied in response to a posting on HackerNews in July. Got a response four days later asking to set up an interview time on Google Hangouts. I responded the same day, he took another day to respond. The interview was set up for the following day. The interview consisted of a single "algorithm" style question where I was asked to implement a function, and then asked how I would improve the runtime. The interviewer seemed a tad confused about his terminology, but we figured each other out in the end. I could not improve the runtime because it's the type of question that encourages you to game by studying interview questions. After admitting I could not answer his question, I asked for the solution, made a mental note of it. I was asked if I had any questions. I asked, he explained. I asked if he had any questions, he didn't. I knew the interview hadn't gone well, and after another four days I received a rejection e-mail.