We present an extension of the in-place BWT algorithm of Crochemore et al. [8] that enables the construction of the Lyndon array using O(1) extra space. Our approach incrementally maintains the lexicographic ranks of the suffixes during the right-to-left BWT construction and then derives the Lyndon array through a simple next-smaller-value procedure. Although not intended for practical use due to its quadratic running time, the method is conceptually simple and works for unbounded alphabets.
@article{arxiv.2512.20869,
title = {In-Place BWT and Lyndon Array Construction in Constant Space},
author = {Felipe A. Louza and Arnaud Lefebvre},
journal= {arXiv preprint arXiv:2512.20869},
year = {2025}
}