Amazon Applied Scientist interview questions

Overall easy interview. Not sure what went wrong. The interview started with Resume/project discussion. Then I was asked a few ML questions on overfitting and underfitting. Later, discussed a use case and design of image matching algorithm. Finally, reverse LinkedList coding question. Answered all the questions, for coding took O(n) space for the first solution and later verbally explained O(1) improvement. Not even a courtesy of leaving feedback. Gah!