Dropbox 电面 Game of Life

Location: San Francisco
First round phone interview.

The interviewer made the question easier by returning the next state of board as opposed to modifying the original input.

After solving the question in about 20 minutes, he then asked to write a few test cases, which I did.

Follow-up question:
What if the board is a million by a million?

He clearly expected some calculation here trying to figure out total size if the board was to be loaded in memory. I told him it was too big to fit into memory. Instead we can load each cell and its surrounding 8 cells at a time. He wasn’t satisfied with my answer.

A week later I was rejected. Overall the interviewer was kind and I expected rejection because I know I didnt answer his followup question well.