IZhO 2010 2-nd round-2
Source:
September 4, 2010
number theorygreatest common divisormodular arithmeticcombinatorics proposedcombinatorics
Problem Statement
In every vertex of a regular -gon exactly one chip is placed. At each one can exchange any two neighbouring chips. Find the least number of steps necessary to reach the arrangement where every chip is moved by positions clockwise from its initial position.