Sortable Software Developer interview questions

I did their online challenge and was called for an on-site interview, which involved a chat with an engineer, a code review and a design problem (an ad server). The interviewers were great and I thought I did well, but did not get an offer.

I applied online without completing the coding challenge. Process took 5-6 weeks until i got first onsite interview. The interview was full day(6 hours long). It was divided in 4 sessions/parts. First was general introduction n resume skills talk. Second round was coding challenge. Third round was code review. Fourth round was ad server design. My experience was good except the interview itself was very tiring. I was at the company location for 6 hours and was expecting more organized interview process but could feel the pressure on interviewers,too. Interview was scheduled for 5:30 hrs and took more than 6:00 hrs in actual!!! Also expected at least 5 mins break between 2 rounds but didn't get any between 3rd and 4th round. Interviewers were very nice and encouraging me to reply. I wish, i knew Java and was good at it when i had my interview, i might have got hired. Also had too much pressure before interview as it was full day interview, prepared for python, algorithm and data structure(which they didn't ask), company technology and ad server design. Overall good experience. Currently working on Java coding skill and would like to apply once again.