In a 3×25 board, 1×3 pieces are placed (vertically or horizontally) so that they occupy entirely 3 boxes on the board and do not have a common point.
What is the maximum number of pieces that can be placed, and for that number, how many configurations are there?[hide=original formulation]
Num tabuleiro 3 × 25 s˜ao colocadas pe¸cas 1 × 3 (na vertical ou na horizontal) de modo que ocupem inteiramente 3 casas do tabuleiro e n˜ao se toquem em nenhum ponto.
Qual ´e o n´umero m´aximo de pe¸cas que podem ser colocadas, e para esse n´umero,
quantas configura¸c˜oes existem?
[url=https://www.obm.org.br/content/uploads/2018/09/Provas_OMCPLP_2018.pdf]source combinatoricscombinatorial geometrymaximum