2001 golf balls which are numbered from 1 to 2001, a few in a box
Source: Singapore Open Math Olympiad 2001 2nd Round p3 SMO
April 2, 2020
combinatoricsDifference
Problem Statement
Suppose that there are golf balls which are numbered from to respectively, and some of these golf balls are placed inside a box. It is known that the difference between the two numbers of any two golf balls inside the box is neither nor . How many such golf balls the box can contain at most? Justify your answer.