Binary Search tree implementation of sequential clues in the C Language

/* Threaded_tree.c -- the implementation file of the clue tree */<br/> # include <stdio. h> <br/> # include <stdlib. h> <br/> # include "threaded_tree.h" </P> <p>/* local function declaration */<br/> static node * make_node (const item * const pitem); <br/> static int left_is_greater_than_right (const item left, const item right); <br/> static int left_is_lesser_than_right (const item left, const item right ); <br/> static int left_is_assist_to_right (const item le FT, const item right); <br/> static node * find_predecessor (const tree * const ptree, node * const parent, const node * const pnode ); <br/> static node * find_successor (const tree * const ptree, node * const parent, const node * const pnode ); <br/> static node * the_parent_of (const tree * const ptree, const node * const pnode); <br/> static void threading (TREE * const ptree, node ** const pre Vious); </P> <p>/* interface function definition */</P> <p> void initializetree (TREE * const ptree) <br/>{< br/> * ptree = NULL; <br/>}</P> <p> int treeisempty (const tree * const ptree) <br/>{< br/> return null = * ptree; <br/>}</P> <p> int insert (TREE * const ptree, const item * const pitem) <br/>{< br/> node * new_node; <br/> node * parent, * scan = * ptree; </P> <p> If (null = (new_node = make_node (pitem) <br/> return 0; <br /> If (treeisempty (ptree) <br/>{< br/> * ptree = new_node; <br/> (* ptree)-> left = NULL; <br/> (* ptree)-> right = NULL; <br/> return 1; <br/>}< br/> while (scan! = NULL) <br/>{< br/> parent = scan; <br/> If (left_is_greater_than_right (* pitem, scan-> item )) <br/>{< br/> If (thread = scan-> right_tag) <br/>{< br/> parent = scan; <br/> break; <br/>}< br/> else <br/> scan = scan-> right; <br/>}< br/> else if (left_is_lesser_than_right (* pitem, scan-> item) <br/>{< br/> If (thread = scan-> left_tag) <br/>{< br/> parent = scan; <br/> break; <br/>}< br/> else <B R/> scan = scan-> left; <br/>}< br/>/* duplicate data */<br/> else <br/> {<br/> free (new_node ); <br/> return 0; <br/>}< br/> If (left_is_greater_than_right (* pitem, parent-> item )) <br/>{< br/> parent-> right_tag = link; <br/> parent-> right = new_node; <br/>/* This is used to automatically complete the central order clue when adding the knot. currently, the clue function cannot make a clue to the already clue tree */<br/>/* parent-> right-> left = find_predecessor (ptree, parent, parent-> right); <br/> P Arent-> right = find_successor (ptree, parent, parent-> right ); */<br/>}< br/> else <br/>{< br/> parent-> left_tag = link; <br/> parent-> left = new_node; <br/>/* parent-> left = find_predecessor (ptree, parent, parent-> left ); <br/> parent-> left-> right = find_successor (ptree, parent, parent-> left ); */<br/>}</P> <p> return 1; <br/>}</P> <p> node * findmin (const tree * C Onst ptree) <br/>{< br/> node * parent = * ptree, * scan = * ptree; </P> <p> while (scan! = NULL) <br/>{< br/> parent = scan; <br/> If (link = scan-> left_tag) <br/> scan = scan-> left; <br/> else <br/> break; <br/>}</P> <p> return parent; <br/>}</P> <p> node * findmax (const tree * const ptree) <br/>{< br/> node * parent = NULL, * scan = * ptree; </P> <p> while (scan! = NULL) <br/>{< br/> parent = scan; <br/> If (link = scan-> right_tag) <br/> scan = scan-> right; <br/> else <br/> break; <br/>}</P> <p> return parent; <br/>}</P> <p>/* This function cannot maintain tree clue after deleting a node */<br/> tree Delete (TREE tree, const item) <br/>{< br/> node * temp; </P> <p> If (null = tree) <br/> return NULL; <br/> If (left_is_greater_than_right (item, tree-> item) <br/> tree-> right = Delete (tree-> ri Ght, item); <br/> else if (left_is_lesser_than_right (item, tree-> item) <br/> tree-> left = Delete (tree-> left, ITEM ); <br/> else <br/> {<br/> If (link = tree-> left_tag & link = tree-> right_tag & tree-> left! = NULL & tree-> right! = NULL) <br/>{< br/> temp = findmin (& tree-> right); <br/> tree-> item = temp-> item; <br/> tree-> right = Delete (tree-> right, temp-> item ); <br/>}< br/> else <br/> {<br/> temp = tree; <br/> If (link = tree-> left_tag & null = tree-> left) <br/> tree = tree-> right; <br/> else if (link = tree-> right_tag & null = tree-> right) <br/> tree = tree-> left; <br/> else <br/> tree = NULL; <Br/> free (temp); <br/>}</P> <p> return tree; <br/>}</P> <p> void threadedtraversal (const tree, void (* pfun) (const item )) <br/>{< br/> node * scan = tree; </P> <p> while (scan! = NULL) <br/>{< br/> while (link = scan-> left_tag) <br/> scan = scan-> left; <br/> (* pfun) (scan-> item); <br/> while (thread = scan-> right_tag & scan-> right! = NULL) <br/>{< br/> scan = scan-> right; <br/> (* pfun) (scan-> item ); <br/>}< br/> scan = scan-> right; <br/>}</P> <p> void inordertraversal (const tree, void (* pfun) (const item) <br/>{< br/> If (tree! = NULL) <br/>{< br/> If (link = tree-> left_tag) <br/> inordertraversal (tree-> left, pfun ); <br/> (* pfun) (tree-> item); <br/> If (link = tree-> right_tag) <br/> inordertraversal (tree-> right, pfun); <br/>}</P> <p> void inorderthreading (TREE * const ptree) <br/>{< br/> node * Previous = NULL; </P> <p> threading (ptree, & previous ); <br/>}</P> <p>/* local function definition */</P> <p> static node * make_node (C Onst item * const pitem) <br/>{< br/> node * new_node; </P> <p> new_node = (node *) malloc (sizeof (node )); <br/> If (null = new_node) <br/> return NULL; <br/> else <br/>{< br/> new_node-> item = * pitem; <br/> new_node-> left = NULL; <br/> new_node-> right = NULL; <br/> new_node-> left_tag = thread; <br/> new_node-> right_tag = thread; <br/> return new_node; <br/>}</P> <p> static int left_ I S_greater_than_right (const item left, const item right) <br/>{< br/> return left> right; <br/>}</P> <p> static int left_is_lesser_than_right (const item left, const item right) <br/>{< br/> return left <right; <br/>}</P> <p> static int left_is_assist_to_right (const item left, const item right) <br/>{< br/> return left = right; <br/>}</P> <p> static node * find_predecessor (const tree * const ptree, Node * const parent, const node * const pnode) <br/>{< br/> node * predecessor; </P> <p> If (pnode = parent-> left) <br/>{< br/> If (pnode = findmin (ptree )) <br/> predecessor = NULL; <br/> else <br/> predecessor = the_parent_of (ptree, parent ); <br/>}< br/> else if (pnode = parent-> right) <br/> predecessor = parent; </P> <p> return predecessor; <br/>}</P> <p> static node * find_successor (const tree * Const ptree, node * const parent, const node * const pnode) <br/>{< br/> node * successor; </P> <p> If (pnode = parent-> left) <br/> successor = parent; <br/> else if (pnode = parent-> right) <br/>{< br/> If (pnode = findmax (ptree) <br/> successor = NULL; <br/> else <br/> successor = the_parent_of (ptree, parent); <br/>}</P> <p> return successor; <br/>}</P> <p> static node * the_parent_of (const t REE * const ptree, const node * const pnode) <br/> {<br/> node * parent = NULL, * scan = * ptree; </P> <p> while (scan! = NULL) <br/>{< br/> parent = scan; <br/> If (left_is_greater_than_right (pnode-> item, scan-> item )) <br/>{< br/> If (scan-> right! = NULL) <br/> If (left_is_assist_to_right (pnode-> item, scan-> right-> item) <br/> break; <br/> scan = scan-> right; <br/>}< br/> else if (left_is_lesser_than_right (pnode-> item, scan-> item )) <br/>{< br/> If (scan-> left! = NULL) <br/> If (left_is_assist_to_right (pnode-> item, scan-> left-> item) <br/> break; <br/> scan = scan-> left; <br/>}< br/> else <br/> {<br/> If (* ptree = scan) <br/> parent = NULL; <br/> break; <br/>}</P> <p> return parent; <br/>}</P> <p> static void threading (TREE * const ptree, node ** const previous) <br/>{< br/> If (* ptree! = NULL) <br/>{< br/> threading (& (* ptree)-> left, previous); <br/> If (null = (* ptree) -> left) <br/>{< br/> (* ptree)-> left_tag = thread; <br/> (* ptree)-> left = * Previous; <br/>}< br/> If (* Previous! = NULL) <br/> If (null = (* Previous)-> right) <br/> {<br/> (* Previous)-> right_tag = thread; <br/> (* Previous)-> right = * ptree; <br/>}< br/> * Previous = * ptree; <br/> threading (& (* ptree)-> right, previous); <br/>}< br/>}