Chapter 2, Building Abstractions with Data
Section - 2.3 Symbolic Data
Exercise 2.66
Here I am evading the implementation of records structure as exercise seems to focus more on the lookup instead of the record.
It can be extended to use record.
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(define (lookup x set)
(cond ((null? set) false)
((= x (entry set)) true)
((< x (entry set))
(lookup x (left-branch set)))
(else
(lookup x (right-branch set)))
)
)
Test/Output:
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; using procedure from previous exercise to build tree.
> (define my-tree (list->tree (list 0 3 4 9 11 20 26 29 35 76 93 97)))
> (lookup 21 my-tree)
#f
> (lookup 0 my-tree)
#t
> (lookup 10 my-tree)
#f
> (lookup 97 my-tree)
#t
> (lookup 35 my-tree)
#t
> (lookup 33 my-tree)
#f
>