;; The first three lines of this file were inserted by DrScheme. They record metadata
;; about the language level of this file in a form that our tools can easily process.
#reader(lib "htdp-beginner-reader.ss" "lang")((modname bst) (read-case-sensitive #t) (teachpacks ((lib "draw.ss" "teachpack" "htdp") (lib "hangman.ss" "teachpack" "htdp"))) (htdp-settings #(#t constructor repeating-decimal #f #t none #f ((lib "draw.ss" "teachpack" "htdp") (lib "hangman.ss" "teachpack" "htdp")))))


;; a node of a binary search tree
;; ssn is an integer representing a social security number
;; name is a symbol representing a name
;; left and right are nodes for left and right subtree
(define-struct node (ssn name left right))

;; define the rest of the tree A 
(define mytree
(make-node
     63
     'a 
     (make-node 29 'b (make-node 15 'c (make-node 10 'd false false) 
                                       (make-node 24 'e false false)) 
                      false)
     (make-node 89 'i false false)))


;; search-bt: integer, binary tree node -> symbol/boolean
;; The function consumes a number n and a binary tree node. 
;; If the tree contains a node structure whose ssn field is n, 
;; the function produces the value of the name field in that node. 
;; Otherwise, the function produces false. 

;; inorder: binary tree node -> a list of integers
;; It consumes a binary tree and produces a list of all the ssn numbers 
;; in the tree. The list contains the numbers in the left-to-right order:
;; the numbers in the left subtree, the number in the node, the
;; numbers in the right subtree

(define (inorder a-node)
   (cond
     [(false? a-node) empty] 
     [else (append 
             (inorder (node-left a-node))
             (list (node-ssn a-node))
             (inorder (node-right a-node))
           )]
   )
)

(inorder false)
(inorder mytree)