red anb black squars in a 3nx3n grid
Source: 1997 Estonia National Olympiad Final Round grade 9 p4
March 13, 2020
combinatoricsgridsquare tableColoring
Problem Statement
In a grid, each square is either black or red. Each red square not on the edge of the grid has exactly five black squares among its eight neighbor squares.. On every black square that not at the edge of the grid, there are exactly four reds in the adjacent squares box. How many black and how many red squares are in the grid?