MathDB
Labelling points

Source: 2017 SDMO High School Problem 5

November 8, 2017

Problem Statement

There are nn dots on the plane such that no three dots are collinear. Each dot is assigned a 00 or a 11. Each pair of dots is connected by a line segment. If the endpoints of a line segment are two dots with the same number, then the segment is assigned a 00. Otherwise, the segment is assigned a 11. Find all nn such that it is possible to assign 00's and 11's to the nn dots in a way that the corresponding line segments are assigned equally many 00's as 11's.