二叉搜索树实现文件C语言(BinarySearchTree.c)

/*  BinarySearchTree.c -- 二叉搜索树实现文件 */
#include <stdio.h>
#include <stdlib.h>
#include "BinarySearchTree.h"

/* 局部函数声明 */
int Left_Is_Less_Than_Right (const Item left, const Item right) ;
int Left_Is_More_Than_Right (const Item left, const Item right) ;
Position Make_Node (const Item item) ;
void Copy_Item_To_Node (Node * * pnode, const Item * pitem) ;

/* 接口函数声明 */

void InitializeTree (Tree * ptree)
{
 *ptree = NULL ;
}

int TreeIsEmpty (const Tree tree)
{
 return NULL == tree ;
}

Position Find (const Tree tree, const Item item)
{
 if (TreeIsEmpty (tree))
  return NULL ;
 if (Left_Is_Less_Than_Right (item, tree -> item))
  return Find (tree -> left, item) ;
 else if (Left_Is_More_Than_Right (item, tree -> item))
  return Find (tree -> right, item) ;
 else
  return tree ;
}

Position FindMin (const Tree tree)
{
 if (TreeIsEmpty (tree))
  return NULL ;
 else if (NULL == tree -> left)
  return tree ;
 else
  return FindMin (tree -> left) ;
}

Position FindMax (const Tree tree)
{
 if (TreeIsEmpty (tree))
  return NULL ;
 else if (NULL == tree -> right)
  return tree ;
 else
  return FindMax (tree -> right) ;
}

Tree Insert (Tree tree, const Item item) 
{
 if (NULL == tree)
 {
  tree = Make_Node (item) ;
  if (NULL == tree)
   return NULL ;
 }
 else if (Left_Is_Less_Than_Right (item, tree -> item))
  tree -> left = Insert (tree -> left, item) ;
 else if (Left_Is_More_Than_Right (item, tree -> item))
  tree -> right = Insert (tree -> right, item) ;
 /* Else item is in the tree already; We'll do nothing */

 return tree ;
}

Tree Delete (Tree tree, const Item item)
{
 Position temp ;

 if (NULL == tree)
  return NULL ;
 else if (Left_Is_Less_Than_Right (item, tree -> item))
  tree -> left = Delete (tree -> left, item) ;
 else if (Left_Is_More_Than_Right (item, tree -> item))
  tree -> right = Delete (tree -> right, item) ;
 /* Found element to be deleted */
 else if (tree -> left && tree -> right)
 {
  temp = FindMin (tree) ;
  Copy_Item_To_Node (&tree, &temp -> item) ;
  tree -> right = Delete (tree -> right, tree -> item) ;
 }
 /* one or zero children <- 我感觉是child, 不过不自信 */
 else
 {
  temp = tree ;
  if (NULL == tree -> left)
   tree = tree -> right ;
  else if (NULL == tree -> right)
   tree = tree -> left ;
  free (temp) ;
 }

 return tree ;
}

void InorderTraversal (const Tree tree, void (* pfun) (const Item item))
{
 if (tree != NULL)
 {
  InorderTraversal (tree -> left, pfun) ;
  (* pfun) (tree -> item) ;
  InorderTraversal (tree -> right, pfun) ;
 }
}

void EmptyTheTree (Tree tree)
{
 if (tree != NULL)
 {
  EmptyTheTree (tree -> left) ;
  EmptyTheTree (tree -> right) ;
  free (tree) ;
 }
}

/* 局部函数定义 */
int Left_Is_Less_Than_Right (const Item left, const Item right)
{
 return left < right ;
}

int Left_Is_More_Than_Right (const Item left, const Item right)
{
 return left > right ;
}

Position Make_Node (const Item item)
{
 Node * new_node ;

 new_node = (Node *) malloc (sizeof (Node)) ;
 if (NULL == new_node)
  return NULL ;
 else
 {
  Copy_Item_To_Node (&new_node, &item) ;
  new_node -> left = NULL ;
  new_node -> right = NULL ;
  return new_node ;
 }
}

void Copy_Item_To_Node (Node * * pnode, const Item * pitem)
{
 (*pnode) -> item = *pitem ;
}