i had a phone call with a recruiter, hr call was pretty nice and polite , more behavourial for the first round , tell me about yourself, pretty fast interview process ,

After a very typical behaviour interview on campus, I was invited to the onsite interview. The HR and a senior developer welcomed me and introduced the company including the working environment. They started with my resume. There were questions about Java and Spring as well as some design patterns questions. Then the senior developer started to ask me the algorithm questions. One was very easy. As long as you took "intro to programming" you would be fine. Another one is a Leetcode hard question which I found after the interview. The hints were unhelpful. I didn't have a clue how to solve it. I eventually failed this interview and received rejection 3 weeks later.