Turkey Junior Olympiad 2009, Part II - P2
Source:
January 20, 2013
Problem Statement
In the beginnig, each square of a strip formed by adjacent squares contains or . At each step, we are writing to the squares containing and to the squares having exactly one neighbour containing , and we are writing s into the other squares. Determine all possible values of such that whatever the initial arrangement of and is, after finite number of steps, all squares can turn into .