MathDB
Bosnia and Herzegovina 2018 TST Day 2 Problem 1

Source: Bosnia and Herzegovina 2018 TST

September 15, 2018
combinatoricsboardmaximumabsolute value

Problem Statement

Every square of 1000×10001000 \times 1000 board is colored black or white. It is known that exists one square 10×1010 \times 10 such that all squares inside it are black and one square 10×1010 \times 10 such that all squares inside are white. For every square KK 10×1010 \times 10 we define its power m(K)m(K) as an absolute value of difference between number of white and black squares 1×11 \times 1 in square KK. Let TT be a square 10×1010 \times 10 which has minimum power among all squares 10×1010 \times 10 in this board. Determine maximal possible value of m(T)m(T)