相比较节点的添加,平衡二叉树的删除要复杂一些。因为在删除的过程中,你要考虑到不同的情况,针对每一种不同的情况,你要有针对性的反应和调整。所以在代码编写的过程中,我们可以一边写代码,一边写测试用例。编写测试用例不光可以验证我们编写的代码是否正确,还能不断提高我们开发代码的自信心。这样,即使我们在开发过程对代码进行修改或者优化也不会担心害怕。然而看起来编写测试用例是一个繁杂的过程,但是从长期的收益来看,编写测试用例的成本是非常低廉的。
在排序二叉树的删除过程当中,我们应该怎么做呢?大家不用担心,只要按照我们下面的介绍一步一步往下做就可以了,大体上分为下面三个步骤:
1)判断参数的合法性,判断参数是否在当前的二叉树当中
2)删除的节点是根节点,此时应该怎么调整
3)删除的节点是普通节点,此时又应该怎么调整
闲话不多说,下面看看我们的代码是怎么设计的?
1、判断参数的合法性,同时判断当前的二叉树是否含有相关数据
1.1 判断输入参数是否合法
STATUS delete_node_from_tree(TREE_NODE** ppTreeNode, int data) { if(NULL == ppTreeNode || NULL == *ppTreeNode) return FALSE; return TRUE; }那么此时测试用例怎么写呢?
static void test1() { TREE_NODE* pTreeNode = NULL; assert(FALSE == delete_node_from_tree(NULL, 10)); assert(FALSE == delete_node_from_tree(&pTreeNode, 10)); }注: 上面的测试用例说明当指针为空或者指针的指针为空,函数返回FALSE。
1.2 判断输入数据是否存在
STATUS delete_node_from_tree(TREE_NODE** ppTreeNode, int data) { TREE_NODE* pTreeNode; if(NULL == ppTreeNode || NULL == *ppTreeNode) return FALSE; pTreeNode = find_data_in_tree_node(*ppTreeNode, data); if(NULL == pTreeNode) return FALSE; return TRUE; }此时,我们设计一种当前指针合法,但是删除数据不存在的测试用例。
static void test2() { TREE_NODE* pTreeNode = NULL; pTreeNode = create_tree_node(10); assert(FALSE == delete_node_from_tree(&pTreeNode, 11)); free(pTreeNode); }注: 上面的测试用例根节点为10,但是删除的数据为11,单步跟踪,验证我们编写的代码是否正确。
2、删除的数据是根节点数据
2.1 删除根数据时,根节点没有左子树,没有右子树情形
/* * * 10 ======> NULL * / * NULL NULL */那么此时代码应该怎么写呢?我们可以试一试。
STATUS delete_node_from_tree(TREE_NODE** ppTreeNode, int data) { TREE_NODE* pTreeNode; 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; } free(pTreeNode); return TRUE; } return TRUE; }我们的代码明显越来越长,我们要保持耐心。此时,该是我们添加新测试用例的时候了。
static void test3() { TREE_NODE* pTreeNode = NULL; pTreeNode = create_tree_node(10); assert(TRUE == delete_node_from_tree(&pTreeNode, 10)); assert(NULL == pTreeNode); }2.2 删除根数据时,只有左子树节点,没有右子树节点
/* * * 10 ======> 5 * / / * 5 NULL 3 NULL * / * 3 */很明显,我们只需要把用左子树节点代替原来的根节点即可。
STATUS delete_node_from_tree(TREE_NODE** ppTreeNode, int data) { TREE_NODE* pTreeNode; 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; } free(pTreeNode); return TRUE; } return TRUE; }这个时候,我们可以添加新的测试用例,分别添加10、5、3,然后删除10。
static void test4() { 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, 3)); assert(TRUE == delete_node_from_tree(&pTreeNode, 10)); assert(5 == pTreeNode->data); assert(NULL == pTreeNode->parent); free(pTreeNode->left_child); free(pTreeNode); }2.3 删除根数据时,没有左子树节点,只有右子树节点
/* * * 10 ======> 15 * / / * NULL 15 NULL 20 * * 20 */上面的代码表示了节点的删除过程。我们可以按照这个流程编写代码。
STATUS delete_node_from_tree(TREE_NODE** ppTreeNode, int data) { TREE_NODE* pTreeNode; 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; } free(pTreeNode); return TRUE; } return TRUE; }添加测试用例,依次添加10、15、20,然后删除数据10。
static void test5() { 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, 10)); assert(15 == pTreeNode->data); assert(NULL == pTreeNode->parent); free(pTreeNode->right_child); free(pTreeNode); }
2.4删除数据的左右节点都存在
2.4 删除节点的左右子树都存在,此时又会分成两种情形
1)左节点是当前左子树的最大节点,此时只需要用左节点代替根节点即可
/* * * 10 ======> 6 * / / * 6 15 5 15 * / * 5 */
代码该怎么编写呢?
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; } } free(pTreeNode); return TRUE; } return TRUE; }
上面的代码中添加的内容表示了我们介绍的这一情形。为此,我们可以设计一种测试用例。依次插入10、6、5、15,然后删除10即可。
static void test6() { 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, 15)); assert(TRUE == delete_node_from_tree(&pTreeNode, 10)); assert(6 == pTreeNode->data); assert(NULL == pTreeNode->parent); assert(15 == pTreeNode->right_child->data); assert(pTreeNode = pTreeNode->right_child->parent); assert(NULL == pTreeNode->parent); free(pTreeNode->left_child); free(pTreeNode->right_child); free(pTreeNode); }
如果上面的测试用例通过,表示我们添加的代码没有问题。
2)左节点不是当前左子树的最大节点,情形如下所示
/* * * 10 ======> 8 * / / * 6 15 5 15 * * 8 */
此时,我们应该用10左侧的最大节点8代替删除的节点10即可。
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 = NULL; pTreeNode = pLeftMax; } } free(pTreeNode); return TRUE; } return TRUE; }
那么,这个场景下面测试用例又该怎么设计呢?其实只需要按照上面给出的示意图进行即可。依次插入数据10、6、8、15,然后删除数据10。
static void test7() { 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 == insert_node_into_tree(&pTreeNode, 15)); assert(TRUE == delete_node_from_tree(&pTreeNode, 10)); assert(8 == pTreeNode->data); assert(NULL == pTreeNode->parent); assert(NULL == pTreeNode->left_child->right_child); assert(NULL == pTreeNode->parent); free(pTreeNode->left_child); free(pTreeNode->right_child); free(pTreeNode); }
至此,删除节点为根节点的情形全部讨论完毕,那么如果删除的节点是普通节点呢,那应该怎么解决呢?
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); }
我们在当前函数的最后一行添加_delete_node_from_tree,这个函数用来处理普通节点的删除情况,我们会在下面一篇博客中继续介绍。
3、 普通节点的删除
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); }