Bloomberg Software Developer Internship interview questions

Interviewers all started off by asking about my past work experience and my various projects. In total, I did one technical phone interview and two technical on campus interviews. I answered the questions all correctly with multiple efficient solutions. For instance, in one of those rounds, I gave an efficient iterative approach and then an efficient recursive approach for the first question. The next question was a string question I solved using two different languages, one where strings are mutable, and the other where strings aren't mutable. Last question was a design question. From all three rounds, I had a total of 8 different problems asked. Was told that I would hear back in a week but three weeks later, I got an email from HR saying that all positions have been filled. I wasn't even given a chance to do a final round on-site. It really breaks your spirit when this happens ... honestly, what could I have possibly done wrong?

The recruiters took my resume at the career fair. I received an invitation to the on-campus interview a few days later. I only made the first two round. The first interviewer was an alumni who was very nice to me.