MathDB

2

Part of 1993 Rioplatense Mathematical Olympiad, Level 3

Problems(1)

integer on each cell of N x N+1

Source: III - Rioplatense 1993 L3 P2

9/19/2022
An integer is written in each cell of a board ofN N rows and N+1N + 1 columns. Prove that some columns (possibly none) can be deleted so that in each row the sum of the numbers left uncrossed out is even.
combinatorics