On the greedy algorithm for the Shortest Common Superstring problem with reversals

Abstract We study a variation of the classical Shortest Common Superstring (SCS) problem in which a shortest superstring of a finite set of strings S is sought containing as a factor every string of S or its reversal. We call this problem Shortest Common Superstring with Reversals (SCS-R). This problem has been introduced by Jiang et al. [9] , who designed a greedy-like algorithm with length approximation ratio 4. In this paper, we show that a natural adaptation of the classical greedy algorithm for SCS has (optimal) compression ratio 1 2 , i.e., the sum of the overlaps in the output string is at least half the sum of the overlaps in an optimal solution. We also provide a linear-time implementation of our algorithm.

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