/* 删除任意值辅助函数 */
rbtree_node _rbtree_delete(rbtree_node h,int key){
if(key < h->key){
if( !is_red(h->left) && !is_red(h->left->left))
h = move_red_left(h);
h->left = _rbtree_delete(h->left,key);
}else{
if( is_red(h->left) )
h = rotate_right(h);
if( key == h->key && h->right == NULL){
free(h);
return NULL;
}
if( !is_red(h->right) && !is_red(h->right->left) )
h = move_red_right(h);
if( key == h->key ){
//TODO:获得最小值
rbtree_node x = _rbtree_min(h->right);
h->key = x->key;
h->val = x->val;
h->right = _rbtree_delete_min(h->right);
}else{
h->right = _rbtree_delete(h->right,key);
}
}
}
/*
* Deletes the leftmost node in the subtree. (Note that "deletes" means "removes from the tree." No memory
* delete operation is actually performed.)
*
* Parameters:
* - ptn = Pointer to root of subtree to have its leftmost node deleted.
*
* Returns:
* Pointer to root of subtree after having the leftmost node deleted.
*
* N.B.:
* This function is recursive; however, the nature of the tree guarantees that the stack space consumed
* by its stack frames will be O(log n).
*/
static PRBTREENODE delete_min(PRBTREENODE ptn)
{
if (!(ptn->ptnLeft))
return rbtNodeRight(ptn);
if (!rbtIsRed(ptn->ptnLeft) && !rbtIsRed(ptn->ptnLeft->ptnLeft))
ptn = move_red_left(ptn);
ptn->ptnLeft = delete_min(ptn->ptnLeft);
return fix_up(ptn);
}
static rbtree_node* delete_min(rbtree_node *h, VALUE *deleted_value) {
if ( !h->left ) {
if(deleted_value)
*deleted_value = h->value;
free(h);
return NULL;
}
if ( !isred(h->left) && !isred(h->left->left) )
h = move_red_left(h);
h->left = delete_min(h->left, deleted_value);
return fixup(h);
}
/*
* Deletes the node in the subtree having an arbitrary key. (Note that "deletes" means "removes from the tree."
* No memory delete operation is actually performed.) An O(log n) operation.
*
* Parameters:
* - ptree = Pointer to the tree head structure, containing the compare function.
* - ptnCurrent = Pointer to the root of the current subtree we're deleting from.
* - key = Key value we're deleting from the tree. It is assumed that this key value exists in the subtree.
*
* Returns:
* Pointer to the root of the subtree after the node has been deleted.
*
* N.B.:
* This function is recursive; however, the nature of the tree guarantees that the stack space consumed
* by its stack frames (and those of delete_min, where we call it) will be O(log n).
*/
static PRBTREENODE delete_from_under(PRBTREE ptree, PRBTREENODE ptnCurrent, TREEKEY key)
{
register TREEKEY keyCurrent = (*(ptree->pfnGetTreeKey))((*(ptree->pfnGetFromNodePtr))(ptnCurrent));
register int cmp = (*(ptree->pfnTreeCompare))(key, keyCurrent);
if (cmp < 0)
{
/* hunt down the left subtree */
if (!rbtIsRed(ptnCurrent->ptnLeft) && !rbtIsRed(ptnCurrent->ptnLeft->ptnLeft))
ptnCurrent = move_red_left(ptnCurrent);
ptnCurrent->ptnLeft = delete_from_under(ptree, ptnCurrent->ptnLeft, key);
}
else
{
if (rbtIsRed(ptnCurrent->ptnLeft))
{
ptnCurrent = rotate_right(ptnCurrent);
keyCurrent = (*(ptree->pfnGetTreeKey))((*(ptree->pfnGetFromNodePtr))(ptnCurrent));
cmp = (*(ptree->pfnTreeCompare))(key, keyCurrent);
}
if ((cmp == 0) && !rbtNodeRight(ptnCurrent))
return ptnCurrent->ptnLeft; /* degenerate case */
if ( !rbtIsRed(rbtNodeRight(ptnCurrent))
&& (!rbtNodeRight(ptnCurrent) || !rbtIsRed(rbtNodeRight(ptnCurrent)->ptnLeft)))
{
ptnCurrent = move_red_right(ptnCurrent);
keyCurrent = (*(ptree->pfnGetTreeKey))((*(ptree->pfnGetFromNodePtr))(ptnCurrent));
cmp = (*(ptree->pfnTreeCompare))(key, keyCurrent);
}
if (cmp == 0)
{
/*
* Here we find the minimum node in the right subtree, unlink it, and link it into place in place of
* ptnCurrent (i.e. node pointed to by ptnCurrent should no longer be referenced). We inherit the
* child pointers and color of ptnCurrent (minus the reference from the right-hand tree where applicable).
*/
register PRBTREENODE ptnMin = find_min(rbtNodeRight(ptnCurrent));
rbtSetNodeRight(ptnMin, delete_min(rbtNodeRight(ptnCurrent)));
ptnMin->ptnLeft = ptnCurrent->ptnLeft;
rbtSetNodeColor(ptnMin, rbtNodeColor(ptnCurrent));
ptnCurrent = ptnMin;
}
else /* hunt down the right subtree */
rbtSetNodeRight(ptnCurrent, delete_from_under(ptree, rbtNodeRight(ptnCurrent), key));
}
return fix_up(ptnCurrent);
}
/*
* 删除最小值辅助函数
*/
rbtree_node _rbtree_delete_min(rbtree_node root){
if(root->left==NULL){
free(root);
return NULL;
}
/*
* 如果向下两个任何一个是红色的,
* 就不用把红色传递下去,因为下面的红色可以
* 用来构成最后删除结点的红色.
* red
* / \
* black black
* /
* black
*
*/
if( !is_red(root->left) && !is_red(root->left->left) ){
root = move_red_left(root);
}
root->left = _rbtree_delete_min(root->left);
return fixup(root);
}