MathDB
interchanging numbers

Source: Baltic Way 2004, problem 12

November 20, 2004
combinatorics unsolvedcombinatorics

Problem Statement

There are 2n2n different numbers in a row. By one move we can interchange any two numbers or interchange any 33 numbers cyclically (choose a,b,ca,b,c and place aa instead of bb, bb instead of cc, cc instead of aa). What is the minimal number of moves that is always sufficient to arrange the numbers in increasing order ?