Class RabinKarp

RabinKarp.java:2–68

import java.util.*;
public class RabinKarp {

    public static void main(String args[])
	{
		Scanner obj = new Scanner(System.in);
		System.out.println("Enter input string");
		String input=obj.nextLine();
		System.out.println("Enter input string");
		String pattern=obj.nextLine();
		rabinKarp(input,pattern);
		
		
	}
    public static int rabinKarp(String str, String pattern) 
    {    
        
        // base
        if(pattern.length()>str.length() || pattern.length()==0) return -1;
      
        
        // rabin - karp
        
	int alphabets=26;
	
        int patternHashCode =  HashFunction(pattern,alphabets);
        
        int window = pattern.length();
        
        int index=-1;
        
        int substringHashCode = HashFunction(str.substring(0,window),alphabets);
                
        for(int i=1;i<str.length()-window+1;i++)
        {
            int prev = str.charAt(i-1) * (int)Math.pow(alphabets,pattern.length()-1);
            
            substringHashCode = (substringHashCode - prev)*alphabets + str.charAt(i+window-1);
            
            if(substringHashCode==patternHashCode)
            {
                if(str.substring(i,i+window).equals(pattern))
                {
                    System.out.println("found at index: "+ i);
                }
            }
        }
        return index;
    }
    
    public static int HashFunction(String inp, int alphabets)
    {
        int k=inp.length()-1;
        
        int res=0;
        
        for(int i=0;i<inp.length();i++)
        {
            int asc = inp.charAt(i);