9 students from 3 countries in a circular table
Source: KJMO 2009 p7
May 2, 2019
combinatoricsCircular permutations
Problem Statement
There are students from Korea, China, and Japan, so total of students are present. How many ways are there to make them sit down in a circular table, with equally spaced and equal chairs, such that the students from the same country do not sit next to each other? If array can become array by rotation, these two arrays are considered equal.