Phone interview involving coding on an online whiteboard. First, the interviewer asked about hash tables and hash functions. Then, he inquired if there were other data structures that could provide a similar index function. I suggested a prefix tree, but he stated that any kind of tree would suffice.

Next, the question focused on linked lists. I was asked how to find nodes with odd values and how to delete them, requiring code to be provided on the online whiteboard. I submitted my code, but the interviewer pointed out several corner cases it did not cover.

Finally, he asked if I had any questions. The entire process lasted approximately 30-40 minutes.

I am not really sure about index data structures. I thought only arrays or hash tables could provide direct indexed access. I still don't understand why trees can offer the same kind of indexing as hash tables.