One very hard math and coding OA, followed by one presentation and coding and techinical interview. Went through everything smoothly but was rejected cuz didn't have too much past internship experience on qr (even though this is a intern role).

I got the first place in one of the competitions held by Jiukun. So I was invited to the interview. 1. Researches I have done as a PhD. 2. coding skills 3. questions about Least Square method.