The HR reached out to me through a recruiting agency, and I had three rounds of interviews.

The first round was a phone screen with HR, which was a typical HR phone screen.

The second round was a technical phone screen with their iOS developer. He was very nice and asked several iOS questions and then one algorithm question.

The third round was an onsite interview with four team members. Firstly, I met another iOS developer. He downloaded one of my previous apps and asked some iOS questions related to the app. Then I met a backend developer, who asked two algorithm questions. They were not too difficult, but I was a little nervous and messed them up. Then I met a designer. He was a web developer at first, then became a great designer. I am interested in UI/UX too, and it was very nice talking with him and hearing how he made the transfer. I was supposed to meet the CTO, but the HR told me they take algorithms very seriously, and I didn't perform well on that, so they decided to cancel the final interview.

Find duplicate numbers in an array.