I'm trying to build a binary tree is lisp. The function should do this
(buildBST ‘(6 9 2 1 7)) -> (6 (2 (1) ()) (9 (7) ()))
The code we have so far will keep returning the error
> 7 nil arguments should be of type real
Here's our code
(defun buildBst (lis)
(cond
((null lis) 0)
((atom lis) lis)
(t (if ( >(car lis)(car(cdr lis)))
(buildBst( cdr lis))
(buildBst(cdr lis))))))
The best approach would be to make an insert function:
(defun tree-insert-element (tree element)
(cond ((tree-null-p tree)
(make-tree element nil nil))
((< (tree-value tree) element)
(make-tree (tree-value tree)
(tree-left tree)
(tree-insert-element (tree-right tree) element)))
(t
(make-tree (tree-value tree)
(tree-insert-element (tree-left tree) element)
(tree-right tree)))))
Thus when you want to insert a whole bunch you can do this:
(defun tree-insert-list (tree list)
(reduce #'tree-insert-element list :initial-value tree))
Of course, you'll need to define the functions the insert function uses as I really don't care how you choose to model a tree. From the look of the expected result I guess make-tree might just wrap list*, but thats not the only way to make a tree!
lisonly has 1 element. You do(> (car lis) (car (cdr lis)), but if there's only 1 element,(car (cdr lis))will beNIL.ifstatement do exactly the same thing? Is that really what you want there?