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Source: 2024 CTST P24

March 29, 2024
combinatorics2024 CTSTexpected value

Problem Statement

Let N=102024N=10^{2024}. SS is a square in the Cartesian plane with side length NN and the sides parallel to the coordinate axes. Inside there are NN points P1P_1, P2P_2, \dots, PNP_N all of which have different xx coordinates, and the absolute value of the slope of any connected line between these points is at most 11. Prove that there exists a line ll such that at least 20242024 of these points is at most distance 11 away from ll.