a square 101 x101 with all cells except one corner cell are black
Source: Tournament of Towns, Junior A-Level , Fall 2019 p7
April 20, 2020
gridColoringcombinatorics
Problem Statement
Peter has a wooden square stamp divided into a grid. He coated some cells of this grid with black ink. After that, he pressed this stamp times on a list of paper so that each time just those cells left a black imprint on the paper. Is it possible that after his actions the imprint on the list is a square such that all the cells except one corner cell are black?(Alexsandr Gribalko)