Adap.tv Software Engineer New Grad interview questions

Met people at career fair. The person whom I talked to was a software engineer and asked me basic questions about my resume and what data structures you used. Working of that data structure internally and its complexity. After two weeks I got an email from HR for scheduling a technical phone interview. The interview went well apart from one problem where I was stuck. When asked for feedback he told I won't be a pessimist and all you did well. I tried following up with HR but no response. No rejection mail nothing.