A Fast Algorithm for Making Su x Arrays and for Burrows-Wheeler Transformation

We propose a fast and memory e cient algorithm for sorting su xes of a text in lexicographic order. It is important to sort su xes because an array of indexes of su xes is called su x array and it is a memory e cient alternative of the su x tree. Sorting su xes is also used for the Burrows-Wheeler transformation in the Block Sorting text compression, therefore fast sorting algorithms are desired. We compare algorithms for making su x arrays of Bentley-Sedgewick, Andersson-Nilsson and Karp-Miller-Rosenberg and making su x trees of Larsson on speed and required memory and propose a new algorithm which is fast and memory e cient by combining them. We also de ne a measure of di culty of sorting su xes: average match length. Our algorithm is e ective when the average match length of a text is large, especially for large databases.