MathDB
The Return of Triangle Geometry

Source: 2023 ISL A7

July 17, 2024

Problem Statement

Let NN be a positive integer. Prove that there exist three permutations a1,,aNa_1,\dots,a_N, b1,,bNb_1,\dots,b_N, and c1,,cNc_1,\dots,c_N of 1,,N1,\dots,N such that ak+bk+ck2N<2023\left|\sqrt{a_k}+\sqrt{b_k}+\sqrt{c_k}-2\sqrt{N}\right|<2023 for every k=1,2,,Nk=1,2,\dots,N.