/** Return the inorder ancestral successor of this BSTNode in a BST, or
* 0 if none.
* PRECONDITION:this BSTNode is a node in a BST.
* POSTCONDITION: the BST is unchanged.
* RETURNS: the BSTNode that is the inorder ancestral successor of this
* BSTNode, or 0 if there is none.
*/
BSTNode<Data>* ancestralSuccessor() {
/* Find and return a successor that is an ancestor, if it exists. */
if (parent==NULL) {
return NULL;
} else if (this==parent->right) {
return parent->ancestralSuccessor();
} else {
return parent;
}
}
BSTNode<Data>* successor() {
/* Determine if the right child or parent is successor. If neither, and
parent exists, find out if one of the parents ancestors is the successor.
If no successor exists, return 0. */
if (right!=NULL) {
return right->leftmostNode();
} else if (parent==NULL) {
return NULL;
} else if (this==parent->left) {
return parent;
} else {
return parent->ancestralSuccessor();
}
}
