![Native string matching algorithm:
It has no pre-processing
phase, needs constant extra space. It always shifts the window by
exactly one position to the right.
It requires 2n expected text characters comparisons.
It finds all valid shifts using a loop that checks the condition
P[1....m]=T[s+1........s+m] for each of the n-m+1 possible values of s .
Consider the following example.
T=ANPANMAN
P=MAN
ANPANMAN](https://image.slidesharecdn.com/naive-161219103833/85/Naive-string-search-2-320.jpg)
Naive string search
- 2. Native string matching algorithm: It has no pre-processing phase, needs constant extra space. It always shifts the window by exactly one position to the right. It requires 2n expected text characters comparisons. It finds all valid shifts using a loop that checks the condition P[1....m]=T[s+1........s+m] for each of the n-m+1 possible values of s . Consider the following example. T=ANPANMAN P=MAN ANPANMAN
- 3. Iterate through the input and the pattern at the same time, comparing their characters to each other. Whenever you get a non-matching character between the two, you can just reset the pattern position and keep the input position as is. This works because the pattern characters are all different, which means that whenever you have a partial match, there can be no other match overlapping with that, so we can just start looking from the end of the partial match.
- 5. Naive string matching algorithm takes time O((n-m+1)m), and this bound is tight in the worst case. The worst case running time is thus O((n-m+1)m). The running time of Naive String Matching algorithm is equal to its matching time, since there is no preprocessing.
- 6. Conclusion: String matching has greatly influenced the field of computer science and will play an important role in future technology. The importance of memory and time efficient string matching algorithm will be increased in computer science. There are many more possible areas in which string matching can play a key role for excelling. Innovation and creativity in string matching can play a immense role for getting time efficient performance in various domains of computer science.
- 7. Thank you