Declaration and initialization of counter array
int [ ] counter = new int [ MAX ] ; for ( int i = 0 ; i < MAX ; i ++ ) counter [ i ] = 0 ; for ( int i = 0 ; i < l / 2 ; i ++ ) counter [ str [ i ] - ' a ' ] ++ ; for ( int i = l / 2 ; i < l ; i ++ ) counter [ str [ i ] - ' a ' ] -- ; for ( int i = 0 ; i < MAX ; i ++ ) if ( counter [ i ] != 0 ) return true ; return false ; }