First question is a robot traveling problem on 2D grid. The 2D grid will feed back a probability (t, x, y) . So it is a 3D dp with time axle plus dfs which requires return the highest probability path at K time. Second question is a binary search on arrays with repeats. Third interview gave me some math problems, and the Fourth interview asked about bst traverse problems, and also ask some conditional probability density function questions. It's ridiculous that this position is machine learning researcher, but they almost did not ask any machine learning questions or related coding questions.