Anagram Substring Search Java

PROGRAM TO PRINT ALL OCCURRENCES OF A PATTERN AND ITS ANAGRAMS(OR PERMUTAATIONS) IN GIVEN STRING

public class MAIN

{

    static final int MAX = 256;

      

    // This function returns true if contents

    // of arr1[] and arr2[] are same, otherwise

    // false.

    static boolean compare(char arr1[], char arr2[])

    {

        for (int i = 0; i < MAX; i++)

            if (arr1[i] != arr2[i])

                return false;

        return true;

    }

  

    // This function search for all permutations

    // of pat[] in txt[]

    static void search(String pat, String txt)

    {

        int M = pat.length();

        int N = txt.length();

  

        // countP[]:  Store count of all 

        // characters of pattern

        // countTW[]: Store count of current

        // window of text

        char[] countP = new char[MAX];

        char[] countTW = new char[MAX];

        for (int i = 0; i < M; i++)

        {

            (countP[pat.charAt(i)])++;

            (countTW[txt.charAt(i)])++;

        }

  

        // Traverse through remaining characters

        // of pattern

        for (int i = M; i < N; i++)

        {

            // Compare counts of current window

            // of text with counts of pattern[]

            if (compare(countP, countTW))

                System.out.println("Found at Index " +

                                          (i - M));

              

            // Add current character to current 

            // window

            (countTW[txt.charAt(i)])++;

  

            // Remove the first character of previous

            // window

            countTW[txt.charAt(i-M)]--;

        }

  

        // Check for the last window in text

        if (compare(countP, countTW))

            System.out.println("Found at Index " + 

                                       (N - M));

    }

  

    /* Driver program to test above function */

    public static void main(String args[])

    {

        String txt = "BACDGABCDA";

        String pat = "ABCD";

        search(pat, txt);

    }

}

OUTPUT

Found at Index 0
Found at Index 5
Found at Index 6

CREDITS: https://www.geeksforgeeks.org/anagram-substring-search-search-permutations/