  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.
