116 lines
No EOL
3.9 KiB
Racket
116 lines
No EOL
3.9 KiB
Racket
#lang racket
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(require rackunit)
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(define-struct node (value left right))
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(define (search node value)
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(cond
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[(empty? node) empty]
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[(= (node-value node) value) node]
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[(> (node-value node) value) (search (node-left node) value)]
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[else (search (node-right node) value)]))
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(define (contains node value)
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(cond
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[(empty? node) #f]
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[(= (node-value node) value) #t]
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[(> (node-value node) value) (contains (node-left node) value)]
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[else (contains (node-right node) value)]))
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(check-true (contains (make-node 3 empty empty) 3))
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(check-false (contains (make-node 3 empty empty) 4))
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(define (insert node value)
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(cond
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[(empty? node) (make-node value empty empty)]
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[(> (node-value node) value) (make-node (node-value node) (insert (node-left node) value) (node-right node))]
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[else (make-node (node-value node) (node-left node) (insert (node-right node) value))]))
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(check-true (contains (insert empty 3) 3))
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(check-false (contains (insert empty 3) 4))
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(define (bst-from-list lst)
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(cond
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[(empty? lst) empty]
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[else (insert (bst-from-list (rest lst)) (first lst))]))
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(check-true (contains (bst-from-list (list 3)) 3))
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(check-true (contains (bst-from-list (list 3 4 2 8)) 2))
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(check-false (contains (bst-from-list (list 3)) 4))
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(check-false (contains (bst-from-list (list 3 7 2 1 5 6)) 4))
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(define (rotate-right node)
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(if (empty? node) empty
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(let ([x node] [l (node-left node)] [r (node-right node)])
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(let ([a (if (empty? l) empty (node-left l))]
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[b (if (empty? l) empty (node-right l))]
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[c (if (empty? r) empty (node-left r))])
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(make-node (node-value l) a (make-node (node-value x) b r))))))
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(define (height node)
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(cond
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[(empty? node) 0]
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[else (+ 1 (max (height (node-left node)) (height (node-right node))))]))
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(define (preorder node)
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(cond
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[(empty? node) empty]
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[else (cons (node-value node) (append (preorder (node-left node)) (preorder (node-right node))))]))
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(define (postorder node)
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(cond
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[(empty? node) empty]
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[else (append (postorder (node-left node)) (postorder (node-right node)) (list (node-value node)))]))
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(define (inorder node)
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(cond
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[(empty? node) empty]
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[else (append (inorder (node-left node)) (cons (node-value node) (inorder (node-right node))))]))
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(check-equal? (inorder (bst-from-list (list 5 2 4 3 7))) (list 2 3 4 5 7))
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(define (avlcheck node)
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(cond
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[(empty? node) 0]
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[(= (avlcheck (node-left node)) -1) -1]
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[(= (avlcheck (node-right node)) -1) -1]
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[(< 1 (abs (- (avlcheck (node-left node)) (avlcheck (node-right node))))) -1]
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[else (+ 1 (max (avlcheck (node-left node)) (avlcheck (node-right node))))]))
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(define (min-subtree node)
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(cond
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[(empty? node) empty]
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[(empty? (node-left node)) node]
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[else (min-subtree (node-left node))]))
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(define (max-subtree node)
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(cond
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[(empty? node) empty]
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[(empty? (node-right node)) node]
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[else (max-subtree (node-right node))]))
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(define (replacement node)
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(cond
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[(empty? node) empty]
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[(empty? (node-left node)) empty]
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[else (max-subtree (node-left node))]))
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(define (sans-max-subtree node)
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(cond
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[(empty? node) empty]
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[(empty? (node-right node)) empty]
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[(empty? (node-right (node-right node))) (make-node (node-value node) (node-left node) empty)]
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[else (make-node (node-value node) (node-left node) (sans-max-subtree (node-right node)))]))
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(define (delete node)
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(cond
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[(empty? node) empty]
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[(empty? (node-left node)) (node-right node)]
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[(empty? (node-right node)) (node-left node)]
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[else (make-node (node-value (replacement node)) (sans-max-subtree (node-left node)) (node-right node))]))
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(check-equal? (delete empty) empty)
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(check-equal? (delete (make-node 5 empty empty)) empty)
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(check-equal? (make-node 5 empty empty) (make-node 5 empty empty))
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(check-equal? (delete (make-node 6 (make-node 2 empty empty) empty)) (make-node 2 empty empty)) |