A 2-approximation algorithm for sorting by prefix reversals

Abstract

Sorting by Prefix Reversals, also known as Pancake Flipping, is the problem of transforming a given permutation into the identity permutation, where the only allowed operations are reversals of a prefix of the permutation. The problem complexity is still unknown, and no algorithm with an approximation ratio better than 3 is known. We present the first polynomial-time 2-approximation algorithm to solve this problem. Empirical tests suggest that the average performance is in fact better than 2. © Springer-Verlag Berlin Heidelberg 2005.