Fill the table with T,M,O
Source: 2021 Thailand Online MO P10 (Mock TMO contest)
April 6, 2021
combinatoricsThailand online MOdesi chudayio physicsknight muth mrnejrha
Problem Statement
Each cell of the board with rows and columns contains exactly one of the three letters , , and in a way that satisfies each of the following conditions:[*] In total, each letter appears exactly of times on the board.
[*] There are no two squares that share a common side and contain the same letter.
[*] Any square contains all three letters , , and .Prove that each letter , , and appears exactly times on every row.