Bloomberg Software Developer interview questions

Got an email that they'd like to interview. Sent a link to a HackerRank lobby that you have to join at an appointed time and wait in. Then they call you. You pick up and they ask basic questions. Then they start the coding exercise. I got a Heat Map question - write an algo that calculates the avg value of a part of the grid. 2D Array question. They didn't want running code, they wanted to see. It was hard for me but I solved it correctly - just not optimally. I could tell the interviewer didn't like my answer though.