Improved Approach for Exact Pattern Matching (Bidirectional Exact Pattern Matching)

Abstract

In this research we present Bidirectional exact pattern matching algorithm [20] in detail. Bidirectional (BD) exact pattern matching (EPM) introduced a new idea to compare pattern with Selected Text Window (STW) of text string by using two pointers (right and left) simultaneously in searching phase. In preprocessing phase Bidirectional EPM algorithm improved the shift decision by comparing rightmost and mismatched character of Partial Text Window (PTW) to the left of pattern at same shift length. The time complexity of preprocessing phase of BD exact pattern matching is O(m) and searching phase takes O(mn/2). The proposed Bidirectional EPM algorithm is effective than the number of existing algorithms in many cases.