int function ( ) { if ( available . isEmpty ( ) ) return - 1 ; int loc0 = available . poll ( ) ; used . add ( loc0 ) ; return loc0 ; }
provide a number which is not assigned to anyone . concode_field_sep int max concode_elem_sep LinkedList<Integer> available concode_elem_sep HashSet<Integer> used concode_field_sep void release concode_elem_sep boolean check