diff --git a/Others/RabinKarp.java b/Others/RabinKarp.java new file mode 100644 index 00000000..ba1e6869 --- /dev/null +++ b/Others/RabinKarp.java @@ -0,0 +1,84 @@ +/** + * @author Prateek Kumar Oraon (https://github.com/prateekKrOraon) + */ +import java.util.Scanner; +import java.lang.Math; + +//An implementation of Rabin-Karp string matching algorithm +//Program will simply end if there is no match +public class RabinKarp { + + public static Scanner scanner = null; + public final static int d = 256; + + public static void main(String[] args){ + + scanner = new Scanner(System.in); + System.out.println("Enter String"); + String text = scanner.nextLine(); + System.out.println("Enter pattern"); + String pattern = scanner.nextLine(); + + int q = 101; + searchPat(text,pattern,q); + + } + + private static void searchPat(String text, String pattern, int q) { + + int m = pattern.length(); + int n = text.length(); + int t = 0; + int p = 0; + int h = 1; + int j = 0; + int i = 0; + + h = (int)Math.pow(d,m-1)%q; + + for(i =0 ; i< m; i++){ + //hash value is calculated for each character and then added with the hash value of the next character for pattern + // as well as the text for length equal to the length of pattern + p = (d*p + pattern.charAt(i))%q; + t = (d*t + text.charAt(i))%q; + } + + for(i=0; i<=n-m;i++){ + + //if the calculated hash value of the pattern and text matches then + //all the characters of the pattern is matched with the text of length equal to length of the pattern + //if all matches then pattern exist in string + //if not then the hash value of the first character of the text is subtracted and hash value of the next character after the end + //of the evaluated characters is added + if(p==t){ + + //if hash value matches then the individual characters are matched + for(j=0;j