On 11/13/2019 10:11 PM, Andrew wrote:
I have this:
(define (related? a1 a2)
(if (equal? a1 a2)
true
(related? (member (rest ("proc that calls list" a1)) (rest ("proc that calls
list" a2)))
(member a1 ("proc that calls list" a2))))))
a1 and a2 are part of a binary search tree and I have another function that
creates a list from the elements of the tree
hence the "proc that calls list"
For some reason, whatever input I'm putting into a1 and a2 is returning only
true, even when I know the answer is suppose to be false
Can anyone guide me onto what's going wrong?
Just guessing, but the empty list is a member of both and all instances
of '() compare eq? (same symbol).
(eq? (list) (list))
=> #t
But if I'm understanding your code correctly, it seems like it would not
work for lists of different lengths.
I think it would be simpler - and probably faster - to create an (obj ->
obj) hash^[1] using eq? compare from the elements of one list and
step though the other list checking if the current element is in the
hash. Or skip the lists entirely and do it directly from the tree walks.
Hope this helps,
George
[1]
https://docs.racket-lang.org/reference/hashtables.html?q=hash#%28def._%28%28quote._~23~25kernel%29._hasheq%29%29
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