Patent ID: 7313555

Claim:
A computer implemented method to compute a two way data structure heur (s, t), wherein s and t are strings or sequences of integers; comprising the steps of: (a) given a range of integers i from 0 to a −1, wherein a is an alphabet size; (b) given a previously-computed data structure input C i,s which stores the number of occurrences of the integer i in a string or sequence of integers s; (c) given a previously-computed data structure input C i,t which stores the number of occurrences of the integer i in a string or sequence of integers t; (d) computing the sum of the absolute values of the difference for all integers i between data structure inputs C i,s and C i,t by the following method: (d1) initializing a variable diffsum to 0; (d2) computing the absolute value of the difference between data structure inputs C i,s and C i,t , and adding the absolute value to the variable diffsum for all integers i from 0 to a −1; and (d3) assigning the variable diffsum in step (d2) as the value of the data structure heur (s, t), wherein the steps in (d) is expressed as the following equation: heur ( s, t )=SIGMA . . . sub. i =0.sup. a −1.vertline. C i,s −C i,t .vertline.