一步一步写算法(之排序二叉树删除-3)

简介: 原文: 一步一步写算法(之排序二叉树删除-3) 【 声明:版权所有,欢迎转载,请勿用于商业用途。  联系信箱:feixiaoxing @163.com】     3 普通节点的删除     3.
原文: 一步一步写算法(之排序二叉树删除-3)

【 声明:版权所有,欢迎转载,请勿用于商业用途。  联系信箱:feixiaoxing @163.com】

    3 普通节点的删除

    3.1 删除的节点没有左子树,也没有右子树

     测试用例1: 删除节点6

/*
*               
*         10          ======>     10
*        /  \                      \
*      6     15                     15
*                                                         
*/

static void test8()
{
	TREE_NODE* pTreeNode = NULL;
	assert(TRUE == insert_node_into_tree(&pTreeNode, 10));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 6));
	assert(6 == pTreeNode->left_child->data);
	assert(TRUE == insert_node_into_tree(&pTreeNode, 15));
	assert(TRUE == delete_node_from_tree(&pTreeNode, 6));
	assert(NULL == pTreeNode->left_child);
	free(pTreeNode->right_child);
	free(pTreeNode);
}
    测试用例2: 删除节点15

/*
*               
*         10          ======>     10
*        /  \                    / 
*      6     15                 6   
*                                                         
*/

static void test9()
{
	TREE_NODE* pTreeNode = NULL;
	assert(TRUE == insert_node_into_tree(&pTreeNode, 10));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 6));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 15));
	assert(15 == pTreeNode->right_child->data);
	assert(TRUE == delete_node_from_tree(&pTreeNode, 15));
	assert(NULL == pTreeNode->right_child);
	free(pTreeNode->right_child);
	free(pTreeNode);
}
    那么代码应该怎么编写呢?

STATUS _delete_node_from_tree(TREE_NODE* pTreeNode)
{
	TREE_NODE* pLeftMax;
	
	if(NULL == pTreeNode-> left_child && NULL == pTreeNode->right_child){
		if(pTreeNode == pTreeNode->parent->left_child)
			pTreeNode->parent->left_child = NULL;
		else
			pTreeNode->parent->right_child = NULL;
	}
	
	free(pTreeNode);
	return TRUE;
}

    3.2 删除的节点有左子树,没有右子树

    测试用例1: 测试节点6

/*
*               
*         10          ======>     10
*        /                      / 
*      6                      3   
*     /
*    3                                                        
*/

static void test10()
{
	TREE_NODE* pTreeNode = NULL;
	assert(TRUE == insert_node_into_tree(&pTreeNode, 10));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 6));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 3));
	assert(TRUE == delete_node_from_tree(&pTreeNode, 6));
	assert(3 == pTreeNode->left_child->data);
	assert(pTreeNode = pTreeNode->left_child->parent);
	free(pTreeNode->left_child);
	free(pTreeNode);
}
    测试用例2: 删除节点15

/*
*               
*         10          ======>     10
*           \                       \
*           15                       12
*            /                    
*           12                                                 
*/

static void test11()
{
	TREE_NODE* pTreeNode = NULL;
	assert(TRUE == insert_node_into_tree(&pTreeNode, 10));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 15));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 12));
	assert(TRUE == delete_node_from_tree(&pTreeNode, 15));
	assert(12 == pTreeNode->right_child->data);
	assert(pTreeNode = pTreeNode->right_child->parent);
	free(pTreeNode->right_child);
	free(pTreeNode);
}
    添加左子树不为空,右子树为空的处理代码,如下所示:

STATUS _delete_node_from_tree(TREE_NODE* pTreeNode)
{
	TREE_NODE* pLeftMax;
	
	if(NULL == pTreeNode-> left_child && NULL == pTreeNode->right_child){
		if(pTreeNode == pTreeNode->parent->left_child)
			pTreeNode->parent->left_child = NULL;
		else
			pTreeNode->parent->right_child = NULL;
	}else if(NULL != pTreeNode->left_child && NULL == pTreeNode->right_child){
		pTreeNode->left_child->parent = pTreeNode->parent;
		
		if(pTreeNode == pTreeNode->parent->left_child)
			pTreeNode->parent->left_child = pTreeNode->left_child;
		else
			pTreeNode->parent->right_child = pTreeNode->left_child;
	}
	
	free(pTreeNode);
	return TRUE;
}

    3.3 删除的节点左子树为空,右子树节点不为空

    测试用例1: 删除数据6

/*
*               
*         10          ======>    10
*        /                     / 
*      6                      8   
*       \
*        8                                                    
*/

static void test12()
{
	TREE_NODE* pTreeNode = NULL;
	assert(TRUE == insert_node_into_tree(&pTreeNode, 10));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 6));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 8));
	assert(TRUE == delete_node_from_tree(&pTreeNode, 6));
	assert(8 == pTreeNode->left_child->data);
	assert(pTreeNode = pTreeNode->left_child->parent);
	free(pTreeNode->left_child);
	free(pTreeNode);
}
    测试用例2: 删除数据15

/*
*               
*        10          ======>    10
*          \                      \ 
*           15                     20 
*             \
*             20                                             
*/

static void test13()
{
	TREE_NODE* pTreeNode = NULL;
	assert(TRUE == insert_node_into_tree(&pTreeNode, 10));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 15));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 20));
	assert(TRUE == delete_node_from_tree(&pTreeNode, 15));
	assert(20 == pTreeNode->right_child->data);
	assert(pTreeNode = pTreeNode->right_child->parent);
	free(pTreeNode->right_child);
	free(pTreeNode);
}
    添加左子树为空,右子树不为空的处理情形。代码如下:

STATUS _delete_node_from_tree(TREE_NODE* pTreeNode)
{
	TREE_NODE* pLeftMax;
	
	if(NULL == pTreeNode-> left_child && NULL == pTreeNode->right_child){
		if(pTreeNode == pTreeNode->parent->left_child)
			pTreeNode->parent->left_child = NULL;
		else
			pTreeNode->parent->right_child = NULL;
	}else if(NULL != pTreeNode->left_child && NULL == pTreeNode->right_child){
		pTreeNode->left_child->parent = pTreeNode->parent;
		
		if(pTreeNode == pTreeNode->parent->left_child)
			pTreeNode->parent->left_child = pTreeNode->left_child;
		else
			pTreeNode->parent->right_child = pTreeNode->left_child;
	}else if(NULL == pTreeNode->left_child && NULL != pTreeNode->right_child){
		pTreeNode->right_child->parent = pTreeNode->parent;
		
		if(pTreeNode == pTreeNode->parent->left_child)
			pTreeNode->parent->left_child = pTreeNode->right_child;
		else
			pTreeNode->parent->right_child = pTreeNode->right_child;
	}
	
	free(pTreeNode);
	return TRUE;
}

    3.4 删除的节点左右子树均不为空,不过又要分为两种情形:

    1) 左节点是删除节点左侧的最大节点 (删除节点6)

/*
*               
*         10          ======>    10
*        /                     / 
*      6                      5    
*    /  \                      \
*   5    8                      8                              
*/

static void test14()
{
	TREE_NODE* pTreeNode = NULL;
	assert(TRUE == insert_node_into_tree(&pTreeNode, 10));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 6));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 5));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 8));
	assert(TRUE == delete_node_from_tree(&pTreeNode, 6));
	assert(5 == pTreeNode->left_child->data);
	assert(pTreeNode = pTreeNode->left_child->parent);
	assert( 8 == pTreeNode->left_child->right_child->data);
	assert(pTreeNode->left_child = pTreeNode->left_child->right_child->parent);
	free(pTreeNode->left_child->right_child);
	free(pTreeNode->left_child);
	free(pTreeNode);
}
    2) 左节点不是删除节点左侧的最大节点(删除节点5)

/*
*               
*         10          ======>    10
*        /                     / 
*       5                      4    
*      / \                    / \
*     2   6                  2   6
*      \                               
*       4
*/

static void test15()
{
	TREE_NODE* pTreeNode = NULL;
	assert(TRUE == insert_node_into_tree(&pTreeNode, 10));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 5));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 2));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 4));
	assert(TRUE == insert_node_into_tree(&pTreeNode, 6));
	assert(TRUE == delete_node_from_tree(&pTreeNode, 5));
	assert(4 == pTreeNode->left_child->data);
	assert(NULL == pTreeNode->left_child->left_child->right_child);
	free(pTreeNode->left_child->left_child);
	free(pTreeNode->left_child->right_child);
	free(pTreeNode->left_child);
	free(pTreeNode);
}
    那么针对这两种类型,我们的代码究竟应该怎么处理呢?

STATUS _delete_node_from_tree(TREE_NODE* pTreeNode)
{
	TREE_NODE* pLeftMax;
	
	if(NULL == pTreeNode-> left_child && NULL == pTreeNode->right_child){
		if(pTreeNode == pTreeNode->parent->left_child)
			pTreeNode->parent->left_child = NULL;
		else
			pTreeNode->parent->right_child = NULL;
	}else if(NULL != pTreeNode->left_child && NULL == pTreeNode->right_child){
		pTreeNode->left_child->parent = pTreeNode->parent;
		
		if(pTreeNode == pTreeNode->parent->left_child)
			pTreeNode->parent->left_child = pTreeNode->left_child;
		else
			pTreeNode->parent->right_child = pTreeNode->left_child;
	}else if(NULL == pTreeNode->left_child && NULL != pTreeNode->right_child){
		pTreeNode->right_child->parent = pTreeNode->parent;
		
		if(pTreeNode == pTreeNode->parent->left_child)
			pTreeNode->parent->left_child = pTreeNode->right_child;
		else
			pTreeNode->parent->right_child = pTreeNode->right_child;
	}else{
		pLeftMax = find_max_node(pTreeNode->left_child);
		if(pLeftMax == pTreeNode->left_child){
			
			if(pTreeNode == pTreeNode->parent->left_child)
				pTreeNode->parent->left_child = pTreeNode->left_child;
			else
				pTreeNode->parent->right_child = pTreeNode->left_child;
			
			pTreeNode->left_child->parent = pTreeNode->parent;
			pTreeNode->left_child->right_child = pTreeNode->right_child;
			pTreeNode->right_child->parent = pTreeNode-> left_child;
			
		}else{
			pTreeNode->data = pLeftMax->data;
			pLeftMax->parent->right_child = pLeftMax->left_child;
			pLeftMax->left_child->parent = pLeftMax->parent;
			pTreeNode = pLeftMax;
		}
	}
	
	free(pTreeNode);
	return TRUE;
}

结束总结:

    上面的过程记录了我们的代码是怎么一步一步走过来的。最后我们给出一份完整的节点删除代码:

STATUS _delete_node_from_tree(TREE_NODE* pTreeNode)
{
	TREE_NODE* pLeftMax;
	
	if(NULL == pTreeNode-> left_child && NULL == pTreeNode->right_child){
		if(pTreeNode == pTreeNode->parent->left_child)
			pTreeNode->parent->left_child = NULL;
		else
			pTreeNode->parent->right_child = NULL;
	}else if(NULL != pTreeNode->left_child && NULL == pTreeNode->right_child){
		pTreeNode->left_child->parent = pTreeNode->parent;
		
		if(pTreeNode == pTreeNode->parent->left_child)
			pTreeNode->parent->left_child = pTreeNode->left_child;
		else
			pTreeNode->parent->right_child = pTreeNode->left_child;
	}else if(NULL == pTreeNode->left_child && NULL != pTreeNode->right_child){
		pTreeNode->right_child->parent = pTreeNode->parent;
		
		if(pTreeNode == pTreeNode->parent->left_child)
			pTreeNode->parent->left_child = pTreeNode->right_child;
		else
			pTreeNode->parent->right_child = pTreeNode->right_child;
	}else{
		pLeftMax = find_max_node(pTreeNode->left_child);
		if(pLeftMax == pTreeNode->left_child){
			
			if(pTreeNode == pTreeNode->parent->left_child)
				pTreeNode->parent->left_child = pTreeNode->left_child;
			else
				pTreeNode->parent->right_child = pTreeNode->left_child;
			
			pTreeNode->left_child->parent = pTreeNode->parent;
			pTreeNode->left_child->right_child = pTreeNode->right_child;
			pTreeNode->right_child->parent = pTreeNode-> left_child;
			
		}else{
			pTreeNode->data = pLeftMax->data;
			pLeftMax->parent->right_child = pLeftMax->left_child;
			pLeftMax->left_child->parent = pLeftMax->parent;			
			pTreeNode = pLeftMax;
		}
	}
	
	free(pTreeNode);
	return TRUE;
}

STATUS delete_node_from_tree(TREE_NODE** ppTreeNode, int data)
{
	TREE_NODE* pTreeNode;
	TREE_NODE* pLeftMax;
	
	if(NULL == ppTreeNode || NULL == *ppTreeNode)
		return FALSE;
	
	pTreeNode = find_data_in_tree_node(*ppTreeNode, data);
	if(NULL == pTreeNode)
		return FALSE;
	
	if(*ppTreeNode == pTreeNode){
		
		if(NULL == pTreeNode->left_child && NULL == pTreeNode->right_child){
			*ppTreeNode = NULL;
		}else if(NULL != pTreeNode->left_child && NULL == pTreeNode->right_child){
			*ppTreeNode = pTreeNode->left_child;
			pTreeNode->left_child->parent = NULL;
		}else if(NULL == pTreeNode->left_child && NULL != pTreeNode->right_child){
			*ppTreeNode = pTreeNode->right_child;
			pTreeNode->right_child->parent = NULL;
		}else{
			pLeftMax = find_max_node(pTreeNode->left_child);
			if(pLeftMax == pTreeNode->left_child){
				*ppTreeNode = pTreeNode->left_child;
				(*ppTreeNode)->right_child = pTreeNode->right_child;
				(*ppTreeNode)->right_child->parent = *ppTreeNode;
				(*ppTreeNode)->parent = NULL;
			}else{
				pTreeNode->data = pLeftMax->data;
				pLeftMax->parent->right_child = pLeftMax->left_child;
				pLeftMax->left_child->parent = pLeftMax->parent;
				pTreeNode = pLeftMax;
			}
		}
		
		free(pTreeNode);
		return TRUE;
	}
	
	return _delete_node_from_tree(pTreeNode);
}


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