42 students split into groups
Source: Vietnamese TST 2012 Problem 6
May 9, 2012
combinatorics unsolvedcombinatorics
Problem Statement
There are students taking part in the Team Selection Test. It is known that every student knows exactly other students. Show that we can divide the students into groups or groups such that the number of students in each group is equal and every two students in the same group know each other.