Method to a difference string for a given string . If string is " adf " then difference string will be " cb " ( first difference 3 then difference 2 )
string getDiffString ( string str ) { string shift = " " ; for ( int i = 1 ; i < str . length ( ) ; i ++ ) { int dif = str [ i ] - str [ i - 1 ] ; if ( dif < 0 ) dif += ALPHA ;