Tantalizing T-tetromino tiling
Source: Philippine Mathematical Olympiad 2020/1
January 19, 2020
PMOcombinatorics
Problem Statement
A T-tetromino is formed by adjoining three unit squares to form a rectangle, and adjoining on top of the middle square a fourth unit square.
Determine the least number of unit squares that must be removed from a grid so that it can be tiled using T-tetrominoes.