Given a chessboard determine if a given black or white piece in a cell is alive / dead. An item is defined alive if it has at least one non-opposite colored or blank neighbor. That was the original question. This is how it morphed over the interview: * The diagonal neighbors don't matter to determine if a piece is alive or dead. * There need not be just 16 pieces of black or white. There can be an arbitrary number of black or white pieces. * If a piece is surrounded by the opposite color in 3 sides, but the 4th side of the same color but is again surrounded by opposite color, then that's still considered dead. (why did you not say this to begin with?!) But it is alive if one of them is blank. * And while calculating the time complexity - she adds, the board can be filled with all black and say one white in the middle or vice versa. How is that a chessboard?! and why are you telling that at minute 45. If we had continued the interview wonder what other additional missing conditions about the problem she would have added that she forgot.

What was the most difficult problem you solved during your last job?