/*rbtree_delete*/
void
mln_sarbt_delete(mln_sarbt_t *t, mln_sarbt_node_t *n)
{
enum sarbt_color y_original_color;
mln_sarbt_node_t *x, *y;
y = n;
y_original_color = y->color;
if (n->left == &(t->nil)) {
x = n->right;
rbtree_transplant(t, n, n->right);
} else if (n->right == &(t->nil)) {
x = n->left;
rbtree_transplant(t, n, n->left);
} else {
y = rbtree_minimum(t, n->right);
y_original_color = y->color;
x = y->right;
if (y->parent == n) x->parent = y;
else {
rbtree_transplant(t, y, y->right);
y->right = n->right;
y->right->parent = y;
}
rbtree_transplant(t, n, y);
y->left = n->left;
y->left->parent = y;
y->color = n->color;
}
if (y_original_color == M_SARB_BLACK) rbtree_delete_fixup(t, x);
n->parent = n->left = n->right = &(t->nil);
}
void util_rbtree_delete(util_rbtree_t *rbtree, util_rbtree_node_t *node)
{
int isblack;
util_rbtree_node_t *temp, *subst;
if((rbtree==NULL) || (node==NULL) || (node==_NULL(rbtree)))
{
return;
}
rbtree->size--;
/* find deleted position, indicated by temp */
if(node->left == _NULL(rbtree))
{
temp = node;
subst = node->right;
}
else if(node->right == _NULL(rbtree))
{
temp = node;
subst = node->left;
}
else /* right & left aren't null */
{
temp = util_rbsubtree_min(node->right, _NULL(rbtree));
if(temp->left != _NULL(rbtree))
{
subst = temp->left;
}
else
{
subst = temp->right;
}
}
if(temp == rbtree->root) /* temp is root */
{
rbtree->root = subst;
util_rbt_black(subst);
rbt_clear_node(temp);
return;
}
isblack = util_rbt_isblack(temp);
/* temp will be removed from it's position, rebuild links
* NOTE: if temp->parent = node, then subst->parent is node
* while node is the one to be delete, so relink subst's parent to temp
* because temp will replace node's in the tree
*/
if(temp->parent == node)
{
subst->parent = temp;
}
else
{
subst->parent = temp->parent;
}
if(temp == temp->parent->left)
{
temp->parent->left = subst;
}
else
{
temp->parent->right = subst;
}
/*
* now temp is removed from the tree.
* so we will make temp to replace node in the tree.
*/
if(temp != node)
{
temp->parent = node->parent;
if(node == rbtree->root) /* node maybe root */
{
rbtree->root = temp;
}
else
{
if(node->parent->left == node)
{
node->parent->left = temp;
}
else
{
node->parent->right = temp;
}
}
temp->right = node->right;
temp->left = node->left;
if(temp->left != _NULL(rbtree))
{
temp->left->parent = temp;
}
if(temp->right != _NULL(rbtree))
{
temp->right->parent = temp;
}
temp->color = node->color;
}
rbt_clear_node(node);
if(isblack)
{
/* temp is black, fix up delete */
rbtree_delete_fixup(rbtree, subst);
}
}
/*
* 删除结点
*
* 参数说明：
* tree 红黑树的根结点
* node 删除的结点
*/
void rbtree_delete(RBRoot *root, Node *node)
{
Node *child, *parent;
int color;
// tree
// / \
// dnode
// / \
// left right
// / \
// replace right
// 被删除节点的"左右孩子都不为空"的情况。
if ( (node->left!=NULL) && (node->right!=NULL) )
{
// 被删节点的后继节点。(称为"取代节点")
// 用它来取代"被删节点"的位置，然后再将"被删节点"去掉。
Node *replace = node;
// 获取后继节点
replace = replace->right;
while (replace->left != NULL)
replace = replace->left;
// "node节点"不是根节点(只有根节点不存在父节点)
if (rb_parent(node))
{
if (rb_parent(node)->left == node)
rb_parent(node)->left = replace;
else
rb_parent(node)->right = replace;
}
else
// "node节点"是根节点，更新根节点。
root->node = replace;
// child是"取代节点"的右孩子，也是需要"调整的节点"。
// "取代节点"肯定不存在左孩子！因为它是一个后继节点。
child = replace->right;
parent = rb_parent(replace);
// 保存"取代节点"的颜色
color = rb_color(replace);
// "被删除节点"是"它的后继节点的父节点"
if (parent == node)
{
parent = replace;
}
else
{
// child不为空
if (child)
rb_set_parent(child, parent);
parent->left = child;
replace->right = node->right;
rb_set_parent(node->right, replace);
}
replace->parent = node->parent;
replace->color = node->color;
replace->left = node->left;
node->left->parent = replace;
if (color == BLACK)
rbtree_delete_fixup(root, child, parent);
free(node);
return ;
}
if (node->left !=NULL)
child = node->left;
else
child = node->right;
parent = node->parent;
// 保存"取代节点"的颜色
color = node->color;
if (child)
child->parent = parent;
// "node节点"不是根节点
if (parent)
{
if (parent->left == node)
parent->left = child;
else
parent->right = child;
}
else
root->node = child;
if (color == BLACK)
rbtree_delete_fixup(root, child, parent);
free(node);
}