CGMO 2021 P3
Source: CGMO 2021 P3
August 14, 2021
combinatoricsColoring
Problem Statement
Find the smallest positive integer , such that one can color every cell of a grid in red, yellow or blue with all the following conditions satisfied:
(1) the number of cells colored in each color is the same;
(2) if a row contains a red cell, that row must contain a blue cell and cannot contain a yellow cell;
(3) if a column contains a blue cell, it must contain a red cell but cannot contain a yellow cell.