Lecture 5 - Brute Force Algorithm

Question 1

What is another name for the brute force algorithm?

Answer 1

Exhaustive search

Question 2

Steps of the naive brute force algorithm?

Answer 2

• set the current starting position in the text to be zero
• compare text and string characters left to right until the entire string is matched or a character mismatches
• in case of mismatch - return to starting position + 1
• in case of a match break and return

Question 3

What is the complexity of the brute force approach?

Answer 3

O(nm)
There are m char comparisons at each (n-(m+1)) char, which is m * n.

Question 4

What complexity of the brute force approach do we expect on average? WHY?

Answer 4

O(n), as typically there will only be one comparison per character to show mismatch.(string not iterated through)