T shape and square
Source: 2022 cjmo P2
March 12, 2022
CJMOcombinatorics
Problem Statement
You have an infinite stack of T-shaped tetrominoes (composed of four squares of side length 1), and an n × n board. You are allowed to place some tetrominoes on the board, possibly rotated, as long as no two tetrominoes overlap and no tetrominoes extend off the board. For which values of n can you cover the entire board?