Found it in collection of Jian Li, CS Department, University of Maryland
Given 2 cyclic strings, both consisting n distinct letter,namely a permuatation of 1 to n.
the problem is to find a rotation of one string that minimize the swap distance.(i.e.the number of swaps of adjacent elements to bring one necklace to the other)
Can you give an O(nlogn) algorithm?
This is a difficult problem. So, think hard!!
Update (11/12/09): Solution in comments !!