Slide on Brute-Force Sequential Search | CSCE 350, Study notes of Computer Science

Download Slide on Brute-Force Sequential Search | CSCE 350 and more Study notes Computer Science in PDF only on Docsity! 1 CSCE 350: Data Structures and Algorithms Chin-Tser Huang huangct@cse.sc.edu University of South Carolina 02/06/2009 2 Announcement Reading assignment: Chapter 3.3 Homework 2 due on Monday, February 9 in class Midterm Exam study guide is posted on class website HW score has been updated at CSE dropbox https://dropbox.cse.sc.edu 02/06/2009 3 Bonus Question Can we solve the problem of computing an in time? ALGORITHM IntExp(n) if n = 0 return 1 else if n mod 2 = 0 return (IntExp(n/2))2 else return (IntExp((n-1)/2))2 × a )(lognΘ 02/06/2009 4 Brute-Force Sequential Search Efficiency: Problem: find a search key in a given list 02/06/2009 5 Brute-Force Sequential Search Efficiency: An enhancement to remove the check on i’s value ← No need to check i<n in every iteration! 02/06/2009 6 Brute-Force String Matching Problem: find a substring in the text that matches the pattern pattern: a string of m characters to search for text: a (longer) string of n characters to search in Brute-force algorithm Step 1 Align pattern at beginning of text Step 2 Moving from left to right, compare each character of pattern to the corresponding character in text until all characters are found to match (successful search); or a mismatch is detected Step 3 While pattern is not found and the text is not yet exhausted, realign pattern one position to the right and repeat Step 2