Years ago I managed to clear super competitive algo/DS rounds for a big firm and then failed spectacularly at the job, because I had no idea what they were talk

Years ago I managed to clear super competitive algo/DS rounds for a big firm and then failed spectacularly at the job, because I had no idea what they were talking about half the time the projects were being discussed. I wish they had just asked more pertinent questions and saved everyone some time and me the humiliation.