Anagram Substring Search ( Or Search for all permutations ) | Java program to search all anagrams of a pattern in a text ; This function returns true if contents of arr1 [ ] and arr2 [ ] are same , otherwise false . ; This function search for all permutations of pat [ ] in txt [ ] ; countP [ ] : Store count of all characters of pattern countTW [ ] : Store count of current window of text ; Traverse through remaining characters of pattern ; Compare counts of current window of text with counts of pattern [ ] ; Add current character to current window ; Remove the first character of previous window ; Check for the last window in text ; Driver program to test above function
public class GFG { static final int MAX = 256 ; static boolean compare ( char arr1 [ ] , char arr2 [ ] ) { for ( int i = 0 ; i < MAX ; i ++ ) if ( arr1 [ i ] != arr2 [ i ] ) return false ; return true ; } static void search ( String pat , String txt ) { int M = pat . length ( ) ; int N = txt . length ( ) ; 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 ) ] ) ++ ; } for ( int i = M ; i < N ; i ++ ) { if ( compare ( countP , countTW ) ) System . out . println ( " Found ▁ at ▁ Index ▁ " + ( i - M ) ) ; ( countTW [ txt . charAt ( i ) ] ) ++ ; countTW [ txt . charAt ( i - M ) ] -- ; } if ( compare ( countP , countTW ) ) System . out . println ( " Found ▁ at ▁ Index ▁ " + ( N - M ) ) ; } public static void main ( String args [ ] ) { String txt = " BACDGABCDA " ; String pat = " ABCD " ; search ( pat , txt ) ; } }