THE ZOOMING METHOD - A RECURSIVE APPROACH TO TIME-SPACE EFFICIENT STRING-MATCHING

A new approach to time-space efficient string-matching is presented. T he method is flexible, its implementation depends whether or not the a lphabet is linearly ordered. The only known linear-time constant-space algorithm for string-matching over nonordered alphabets is the Galil- Seiferas algorithm, see Crochemore (1993) and Galil (1983) which are r ather complicated. The zooming method gives probably the simplest stri ng-matching algorithm working in constant space and linear time for no nordered alphabets. The novel feature of our algorithm is the applicat ion of the searching phase (which is usually simpler than preprocessin g) in the preprocessing phase. The preprocessing has a recursive struc ture similar to selection in linear time, see Aho (1974). For ordered alphabets the preprocessing part is much simpler, its basic component is a simple and well-known algorithm for finding the maximal suffix, s ee Duval (1983). Hence we demonstrate a new application of this algori thm, see also Crochemore (1991). The idea of the zooming method was ap plied by Crochemore et al. (1995) to two-dimensional patterns.