TBO.com Sr. Software Engineer interview questions

I was asked to design meeting scheduler. I started with flow, defined actors, created UML. When I asked if it is fine, he agreed. I started creating classes, and methods. All this while, when asked if there is anything specific he is looking, or thinks some issues, he was fine. He hardly said anything. Towards end, when I completed the code, he said, Oh you are done? Like I was speaking since 40 mins, and it was like he was working on something else, and not listening. Obviously, when your interviewer isn't interested, you will be rejected. In the feedback, he said poor design. Like if he wanted anything specific, he should have asked. Overall I will say, it as a bad luck. God help those, for whose he is the interviewer.

Interviewer was friendly. It was good. Questions were not hard. Interview was taken online. HR does not reply over mail for some reason. Interviewer explained about the company culture and tech stack being used by their teams.