static void printAllKLengthRec ( char [ ] set , String prefix , int n , int k ) {
  if ( k == 0 ) {
    System . out . println ( prefix ) ;
    return ;
  }
  for ( int i = 0 ;
  i < n ;
  ++ i ) {
    String newPrefix = prefix + set [ i ] ;
    printAllKLengthRec ( set , newPrefix , n , k - 1 ) ;
  }
}

static void printAllKLengthRec ( char [ ] set , String prefix , int n , int k ) { if ( k == 0 ) { System . out . println ( prefix ) ; return ; } for ( int i = 0 ; i < n ; ++ i ) { String newPrefix = prefix + set [ i ] ; printAllKLengthRec ( set , newPrefix , n , k - 1 ) ; } }
(method_declaration (modifiers) type: (void_type) name: (identifier) parameters: (formal_parameters (formal_parameter type: (array_type element: (integral_type) dimensions: (dimensions)) name: (identifier)) (formal_parameter type: (type_identifier) name: (identifier)) (formal_parameter type: (integral_type) name: (identifier)) (formal_parameter type: (integral_type) name: (identifier))) body: (block (if_statement condition: (parenthesized_expression (binary_expression left: (identifier) right: (decimal_integer_literal))) consequence: (block (expression_statement (method_invocation object: (field_access object: (identifier) field: (identifier)) name: (identifier) arguments: (argument_list (identifier)))) (return_statement))) (for_statement init: (local_variable_declaration type: (integral_type) declarator: (variable_declarator name: (identifier) value: (decimal_integer_literal))) condition: (binary_expression left: (identifier) right: (identifier)) update: (update_expression (identifier)) body: (block (local_variable_declaration type: (type_identifier) declarator: (variable_declarator name: (identifier) value: (binary_expression left: (identifier) right: (array_access array: (identifier) index: (identifier))))) (expression_statement (method_invocation name: (identifier) arguments: (argument_list (identifier) (identifier) (identifier) (binary_expression left: (identifier) right: (decimal_integer_literal)))))))))