[plt-scheme] Help: I want to travel a binary tree?

On 7/30/07, Zeng Fucen <zengfucen at gmail.com> wrote:
>
> I'm a scheme novice,
>
> I want to travel a binary tree, how to ? (depth first)
>
> Thanks for your tips , first!
>
> I define a tree like this:  (1 (2 4 5) (3 6 7))
>
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The syntax for defining a list of any sort is either:
(list ...)
'(...) <- What's inside will NOT be evaluated.

Hans gave a nice example:

"(1 (2 (4 () ()) (5 () ())) (3 (6 () ()) (7 () ()))"

You don't *need* it, but it makes more sense that way.

(define (travel-tree l)
   (cond ((null? l) ())
            ((list? l) (travel-tree (car l)))
            (t (travel-tree (cdr l))))

The above method _should_ work, but I can't guarantee it because I have my
own problems.
I assume that it'll be tail-recursive, considering that it will not evaluate
the rest of the condition if it succeeds.

All in all, I hope this helps.
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