X' - O in 10 x10 board
Source: All-Russian MO 2009 Regional 11. 2
August 28, 2024
combinatorics
Problem Statement
In some cells of the table arranged several 's and a few 's. It is known that there is no line (row or column) completely filled with identical symbols (crosses or zeros). However, if in any empty If you place any icon in a cell, this condition will be violated. What is the minimum number of icons that can appear in a table?