Chessboard Infection

On a standard 8×8 chessboard there are 7 infected cells. Every minute each cell which has at least 2 infected neighbors gets infected as well. Is it possible for the entire chessboard to get infected eventually?

The total perimeter of the infected regions never increases. If there are 7 infected cells initially, their total perimeter is at most 28. The perimeter of an 8×8 square is 32. Therefore, it is impossible to infect the entire chessboard.

+ posts

We do not know where this puzzle originated from. If you have any information, please let us know via email.

Notify of
Oldest Most Voted
Inline Feedbacks
View All Comments