Pergunta de entrevista da empresa GoodWorker

Interviewer asked me longest palindromic substring question. First i solved in n*3 through brute force. After that i solved in n*2 using dp.After solved with this approach inrerviewer was not happy.He asked me that this solution is complex we can solved using binary search. I told him that binary search will not work but he was not satisfy. Interviewer have no proper knowledge about Dsa. How can he select right candidates based on dsa. I gave an interview for backend but interviewer never worked on backend. He was purely frontend guy. Completely negative experience.