An Efficient Implementation of Manacher's Algorithm

Manacher’s algorithm has been shown to be optimal to the longest palindromic substring problem. Many of the existing implementations of this algorithm, however, unanimously required in-memory construction of an augmented string that is twice as long as the original string. Although it has found widespread use, we found that this preprocessing is neither economic nor necessary. We present a more efficient implementation of Manacher’s algorithm based on index mapping that makes the string augmentation process obsolete.