;teil 2

(define code
    (lambda (tree message)
      (if  (empty? message)
           empty
           (append  (code-symbol tree (first message))
                    (code tree (rest message))))))

(define code-symbol
    (lambda (tree symbol)
     (cond ((empty? (first (node-symbols tree))) (violation "Symbol nicht im Tree"))
           ((help-symbolsearch (node-symbols tree) symbol)
             (cond ((help-symbolsearch (node-symbols (node-left tree)) symbol) (cons 0 (code-symbol (node-left tree) symbol)))
                   ((help-symbolsearch (node-symbols (node-right tree)) symbol) (cons 1 (code-symbol (node-left tree) symbol))))))))

   (define help-symbolsearch
     (lambda (s symbol)
       (cond ((empty? (first s))  (violation "Symbol nicht im Tree"))
             ((string=? (first s) symbol) #t)
             (else (help-symbolsearch (rest s) symbol)))))