dominoes on a red-blue nxn boad, colourful dominoes with no overlaps
Source: Dutch BxMO/EGMO TST 2015 p3
August 24, 2019
combinatoricsColoringboard
Problem Statement
Let be a positive integer. Each square of an n\times n board is coloured red or blue. We put dominoes on the board, each covering two squares of the board. A domino is called even if it lies on two red or two blue squares and colourful if it lies on a red and a blue square. Find the largest positive integer having the following property: regardless of how the red/blue-colouring of the board is done, it is always possible to put non-overlapping dominoes on the board that are either all even or all colourful.