Got first phone screening and progressed to second round which consisted of a problem set, and then two further meetings with team members. While in the middle of the problem set, I was told to stop immediately. I never got to meet the other two people. Apparently, the CEO had made the decision to extend the offer to another candidate at that very moment. The person who was initially interviewing me/ overseeing the completion of the problem set had no answer as to what just happened. All that they could say was "apologies....". Seems that they make impulsive decisions without an explanation (or maybe they don't feel that they owe you an explanation as an interviewee). A couple weeks later, the same job was posted on LinkedIn. So maybe the person didn't take the offer? Not really sure but this was a horrible interview experience, and was a really bad look for the company.