MathDB
rectangle that contains 20 marked cells out of 40 cells on infinite chessboard

Source: Tournament of Towns 2020 oral p3 (15 March 2020)

May 18, 2020
combinatoricscombinatorial geometrygrid

Problem Statement

4040 cells were marked on an infinite chessboard. Is it always possible to find a rectangle that contains 2020 marked cells?
M. Evdokimov