checkers on a 8x8 chessboard
Source: Indian Postal Coaching 2008 set 4 p4
May 25, 2020
combinatoricsChessboard
Problem Statement
An square board is divided into unit squares. A ’skew-diagonal’ of the board is a set of unit squares no two of which are in the same row or same column. Checkers are placed in some of the unit squares so that ’each skew-diagonal contains exactly two squares occupied by checkers’. Prove that there exist two rows or two columns which contain all the checkers.