100 colors for 50x50 table, 1x2 tile related condition
Source: 2023 South Russian Girls MO - Assara Juniors p4 / M2774 in no. 11-12 of Kvant, 2023
February 28, 2024
combinatoricsColoring
Problem Statement
In a checkered square, each cell is painted in one of given colors so that all colors are present and it is impossible to cut a single-color domino from the square (i.e. a rectangle). Galiia wants to recolor all the cells of one of the colors into another color (out of the given colors) so that this condition is preserved (i.e., it is still impossible to cut out a domino of the same color). Is it true that Galiia will definitely be able to do this?