二叉搜索树的相关操作（增删查改）---非递归实现

版权声明：本文为博主原创文章，未经博主允许不得转载。 https://blog.csdn.net/better12038/article/details/85309781

//BSTree.h
//非递归实现

#pragma once
#include <stdio.h>
#include <stdlib.h>
#include <windows.h>

typedef struct BSTreeNode
{
	int key;
	struct BSTreeNode *left;
	struct BSTreeNode *right;
}BSTreeNode;

//查找:找到返回0，找不到返回-1
int BSTreeSearch(BSTreeNode *root, int key)
{
	BSTreeNode *cur = root;
	while (cur != NULL)
	{
		if (cur->key == key)
		{
			printf("找到\n");
			return 0;
		}
		if (cur->key < key)
		{
			cur = cur->right;
		}
		else
			cur = cur->left;
	}
	printf("没找到\n");
	return -1;
}

//插入
 int BSTreeInsert(BSTreeNode **root, int key)
{
	BSTreeNode *parent = NULL;
	BSTreeNode *cur = *root;
	while (cur != NULL)
	{
		if (cur->key == key)
			return -1;
		parent = cur;
		if (key < cur->key)
			cur = cur->left;
		else
			cur = cur->right;
	}

	BSTreeNode *node = (BSTreeNode *)malloc(sizeof(*node));
	node->key = key;
	node->left = node->right = NULL;
	if (parent == NULL)
	{
		*root = node;
		return 0;
	}
	if (key < parent->key)
	{
		parent->left = node;
	}
	else
		parent->right = node;
	return 0;

}

 //删除，根据节点删
 void Remove(BSTreeNode **root, BSTreeNode *parent, BSTreeNode *cur)
 {
	 //要删除节点的左子树为空
	 if (cur->left == NULL)
	 {
		 if (parent == NULL)
		 {
			 *root = cur->right;
			 free(cur);
			 return;
		 }
		 else if (cur == parent->left)
		 {
			 parent->left = cur->right;
			 free(cur);
			 return;
		 }
		 else 
		 {
			 parent->right = cur->right;
			 free(cur);
			 return;
		 }
	 }
	 //要删除节点的右子树为空
	 else if (cur->right == NULL)
	 {
		 if (parent == NULL)
		 {
			 *root = cur->left;
			 free(cur);
			 return;
		 }
		 else if (cur == parent->right)
		 {
			 parent->right = cur->left;
			 free(cur);
			 return;
		 }
		 else
		 {
			 parent->left = cur->left;
			 free(cur);
			 return;
		 }
	 }
		//要删除节点的左右子树都不为空,用替换法删除,找右子树中最小的
	 else
	 {
		 BSTreeNode *del = cur->right;
		 BSTreeNode *delParent = cur;
		 if (del->left != NULL)
		 {
			 delParent = del;
			 del = del->left;
		 }
		 cur->key = del->key;
		 if (delParent == cur)
		 {
			 delParent->right = del->right;
		 }
		 else
			 delParent->left = del->right;
		 free(del);
	 }
	 
 }

//删除，按照节点删
 int BSTreeRemove(BSTreeNode **root, int key)
 {
	 BSTreeNode *cur = *root;
	 BSTreeNode *parent = NULL;
	 while (cur != NULL)
	 {
		 if (key == cur->key)
		 {
			 Remove(root, parent, cur);
			 return 0;
		 }
		 parent = cur;
		 if (key < cur->key)
		 {
			 cur = cur->left;
		 }
		 else
		 {
			 cur = cur->right;
		 }
	 }
	 return -1;
 }

//打印
int BSTreePrint(BSTreeNode *root)
{
	if (root != NULL)
	{
		printf("%d\n", root->key);
		if (root->left != NULL)
		{
			printf("%d\n", BSTreePrint(root->left));

		}
		if (root->right != NULL)
		{
			printf("%d\n", BSTreePrint(root->right));
		}
	}
	//printf("\n");
	return 0;
}

void test()
{
	BSTreeNode *bs = NULL;
	BSTreeInsert(&bs, 2);
	BSTreeInsert(&bs, 1);
	BSTreeInsert(&bs, 3);
	BSTreeSearch(bs, 2);
	BSTreeSearch(bs, 4);
	BSTreeSearch(bs, 3);
	BSTreePrint(bs);

	BSTreeRemove(&bs, 1);
	BSTreePrint(bs);
}