MathDB
Array of numbers with 1 and -1

Source: 1962 All-Soviet Union Olympiad

January 15, 2018
Russiacombinatorics

Problem Statement

An n×nn \times n array of numbers is given. nn is odd and each number in the array is 11 or −1-1. Prove that the number of rows and columns containing an odd number of −1-1s cannot total nn.
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