Combinatorics
Source: Pan African Mathematics Olympiad P3
August 15, 2024
PAMO 2024
Problem Statement
Given an integer , Jo-Ané alternately writes crosses () and circles () in the cells of a square grid with rows and columns: she first writes a cross in a cell, then a circle in a second cell, then a cross in a third cell, and so on. When the table is completely filled, her score is calculated as the sum , where is the number of rows containing more crosses than circles and is the number of columns containing more circles than crosses.Determine, in terms of , the highest possible score that Jo-Ané can obtain..