text: Vectors to store the lowercase and uppercase characters
code: Vector < Character > v1 = new Vector < > ( ) ; Vector < Character > v2 = new Vector < > ( ) ; for ( int i = 0 ; i < n ; i ++ ) { if ( s . charAt ( i ) >= ' a ' && s . charAt ( i ) <= ' z ' ) v1 . add ( s . charAt ( i ) ) ; if ( s . charAt ( i ) >= ' A ' && s . charAt ( i ) <= ' z ' ) v2 . add ( s . charAt ( i ) ) ; }