I was asked a problem that needed to output differences in an n-ary graph and output as a count. I was able to solve it by doing preprocessing of recording subtree sizes and hence solve it in O (n)

next was design interview for posting reviews

next was sudoku : isValid and solveSudoku

I was able to solve both with a hiccup in boxId calculation. I recovered from that but fell just short of outputting correctly. It felt to me that the time for this interview is way too short to accomplish both problems if you have not seen them before and slightly short even if you have seen but might encounter minor programming errors and you need to debug.