MathDB
maximum no of L-dominoes on a n x n board

Source: 2021 Bosnia Herzegovina MO p4, posted as TST inside contest collections, 13.6.2021

October 7, 2022
combinatorics

Problem Statement

An L-shaped figure composed of 44 unit squares (such as shown in the picture) we call L-dominoes. https://cdn.artofproblemsolving.com/attachments/b/2/064b7c7de496f981cd937cbb7392efc1066420.png Determine the maximum number of L-dominoes that can be placed on a board of dimensions n×nn \times n, where nn is natural number, so that no two dominoes overlap and it is possible get from the upper left to the lower right corner of the board by moving only across those squares that are not covered by dominoes. (By moving, we move from someone of the square on it the neighboring square, i.e. the square with which it shares the page).
Note: L-Dominoes can be rotated as well as flipped, giving an symmetrical figure wrt axis compared to the one shown in the picture.