necklace, min. # of colorings to distinguish beads
Source: VJIMC 2007 1.2
June 24, 2021
combinatorics
Problem Statement
Alice has got a circular key ring with keys, . When she takes it out of her pocket, she does not know whether it got rotated and/or flipped. The only way she can distinguish the keys is by coloring them (a color is assigned to each key). What is the minimum number of colors needed?