Moves on a 5 x 5 board
Source: 2012 Baltic Way, Problem 9
November 22, 2012
combinatorics unsolvedcombinatorics
Problem Statement
Zeroes are written in all cells of a board. We can take an arbitrary cell and increase by 1 the number in this cell and all cells having a common side with it. Is it possible to obtain the number 2012 in all cells simultaneously?