二叉搜索树中序线索化实现文件C语言

/* threaded_tree.c -- 线索树实现文件 */ #include <stdio.h> #include <stdlib.h> #include "threaded_tree.h" /* 局部函数声明 */ static Node * Make_Node (const Item * const pitem) ; static int Left_Is_Greater_Than_Right (const Item left, const Item right) ; static int Left_Is_Lesser_Than_Right (const Item left, const Item right) ; static int Left_Is_Equal_To_Right (const Item left, const Item right) ; static Node * Find_Predecessor (const Tree * const ptree, Node * const parent, const Node * const pnode) ; static Node * Find_Successor (const Tree * const ptree, Node * const parent, const Node * const pnode) ; static Node * The_Parent_Of (const Tree * const ptree, const Node * const pnode) ; static void Threading (Tree * const ptree, Node * * const previous) ; /* 接口函数定义 */ void InitializeTree (Tree * const ptree) { *ptree = NULL ; } int TreeIsEmpty (const Tree * const ptree) { return NULL == *ptree ; } int Insert (Tree * const ptree, const Item * const pitem) { Node * new_node ; Node * parent, * scan = *ptree ; if (NULL == (new_node = Make_Node (pitem))) return 0 ; if (TreeIsEmpty (ptree)) { *ptree = new_node ; (*ptree) -> left = NULL ; (*ptree) -> right = NULL ; return 1 ; } while (scan != NULL) { parent = scan ; if (Left_Is_Greater_Than_Right (*pitem, scan -> item)) { if (THREAD == scan -> right_tag) { parent = scan ; break ; } else scan = scan -> right ; } else if (Left_Is_Lesser_Than_Right (*pitem, scan -> item)) { if (THREAD == scan -> left_tag) { parent = scan ; break ; } else scan = scan -> left ; } /* 出现重复数据 */ else { free (new_node) ; return 0 ; } } if (Left_Is_Greater_Than_Right (*pitem, parent -> item)) { parent -> right_tag = LINK ; parent -> right = new_node ; /* 此处用来完成在添加结点时自动完成中序线索化.当前线索化函数无法对已线索化的树进行线索化 */ /* parent -> right -> left = Find_Predecessor (ptree, parent, parent -> right) ; parent -> right -> right = Find_Successor (ptree, parent, parent -> right) ; */ } else { parent -> left_tag = LINK ; parent -> left = new_node ; /* parent -> left -> left = Find_Predecessor (ptree, parent, parent -> left) ; parent -> left -> right = Find_Successor (ptree, parent, parent -> left) ; */ } return 1 ; } Node * FindMin (const Tree * const ptree) { Node * parent = *ptree , * scan = *ptree ; while (scan != NULL) { parent = scan ; if (LINK == scan -> left_tag) scan = scan -> left ; else break ; } return parent ; } Node * FindMax (const Tree * const ptree) { Node * parent = NULL, * scan = *ptree ; while (scan != NULL) { parent = scan ; if (LINK == scan -> right_tag) scan = scan -> right ; else break ; } return parent ; } /* 此函数无法完成删除结点后维持树的线索化 */ Tree Delete (Tree tree, const Item item) { Node * temp ; if (NULL == tree) return NULL ; if (Left_Is_Greater_Than_Right (item, tree -> item)) tree -> right = Delete (tree -> right, item) ; else if (Left_Is_Lesser_Than_Right (item, tree -> item)) tree -> left = Delete (tree -> left, item) ; else { if (LINK == tree -> left_tag && LINK == tree -> right_tag && tree -> left != NULL && tree -> right != NULL) { temp = FindMin (&tree -> right) ; tree -> item = temp -> item ; tree -> right = Delete (tree -> right, temp -> item) ; } else { temp = tree ; if (LINK == tree -> left_tag && NULL == tree -> left) tree = tree -> right ; else if (LINK == tree -> right_tag && NULL == tree -> right) tree = tree -> left ; else tree = NULL ; free (temp) ; } } return tree ; } void ThreadedTraversal (const Tree tree, void (* pfun) (const Item item)) { Node * scan = tree ; while (scan != NULL) { while (LINK == scan -> left_tag) scan = scan -> left ; (* pfun) (scan -> item) ; while (THREAD == scan -> right_tag && scan -> right != NULL) { scan = scan -> right ; (* pfun) (scan -> item) ; } scan = scan -> right ; } } void InorderTraversal (const Tree tree, void (* pfun) (const Item item)) { if (tree != NULL) { if (LINK == tree -> left_tag) InorderTraversal (tree -> left, pfun) ; (* pfun) (tree -> item) ; if (LINK == tree -> right_tag) InorderTraversal (tree -> right, pfun) ; } } void InorderThreading (Tree * const ptree) { Node * previous = NULL ; Threading (ptree, &previous) ; } /* 局部函数定义 */ static Node * Make_Node (const Item * const pitem) { Node * new_node ; new_node = (Node *) malloc (sizeof (Node)) ; if (NULL == new_node) return NULL ; else { new_node -> item = *pitem ; new_node -> left = NULL ; new_node -> right = NULL ; new_node -> left_tag = THREAD ; new_node -> right_tag = THREAD ; return new_node ; } } static int Left_Is_Greater_Than_Right (const Item left, const Item right) { return left > right ; } static int Left_Is_Lesser_Than_Right (const Item left, const Item right) { return left < right ; } static int Left_Is_Equal_To_Right (const Item left, const Item right) { return left == right ; } static Node * Find_Predecessor (const Tree * const ptree, Node * const parent, const Node * const pnode) { Node * predecessor ; if (pnode == parent -> left) { if (pnode == FindMin (ptree)) predecessor = NULL ; else predecessor = The_Parent_Of (ptree, parent) ; } else if (pnode == parent -> right) predecessor = parent ; return predecessor ; } static Node * Find_Successor (const Tree * const ptree, Node * const parent, const Node * const pnode) { Node * successor ; if (pnode == parent -> left) successor = parent ; else if (pnode == parent -> right) { if (pnode == FindMax (ptree)) successor = NULL ; else successor = The_Parent_Of (ptree, parent) ; } return successor ; } static Node * The_Parent_Of (const Tree * const ptree, const Node * const pnode) { Node * parent = NULL, * scan = *ptree ; while (scan != NULL) { parent = scan ; if (Left_Is_Greater_Than_Right (pnode -> item, scan -> item)) { if (scan -> right != NULL) if (Left_Is_Equal_To_Right (pnode -> item, scan -> right -> item)) break ; scan = scan -> right ; } else if (Left_Is_Lesser_Than_Right (pnode -> item, scan -> item)) { if (scan -> left != NULL) if (Left_Is_Equal_To_Right (pnode -> item, scan -> left -> item)) break ; scan = scan -> left ; } else { if (*ptree == scan) parent = NULL ; break ; } } return parent ; } static void Threading (Tree * const ptree, Node * * const previous) { if (*ptree != NULL) { Threading (&(*ptree) -> left, previous) ; if (NULL == (*ptree) -> left) { (*ptree) -> left_tag = THREAD ; (*ptree) -> left = *previous ; } if (*previous != NULL) if (NULL == (*previous) -> right) { (*previous) -> right_tag = THREAD ; (*previous) -> right = *ptree ; } *previous = *ptree ; Threading (&(*ptree) -> right, previous) ; } }