void
Tree_Delete (
NODE **root,
NODE *z
)
{
NODE *y;
if (!z->left) {
//either z->right is null (no child)
//or z->right only (replace z with z->right)
printf ("case 1:\n");
Transplant (root, z, z->right);
} else if (!z->right) {
//z->left only, replace z with z->left
printf ("case 2:\n");
Transplant (root, z, z->left);
} else {
//z->left and z->right are valid,
//find successor(z):
y = Tree_Successor (z); //y must in the right subtree of z
printf ("successor of %d is:\n", z->key);
Print_Node (y);
// //for debug
// if (y) {
// printf ("successor: key = %d, p = 0x%x, left = 0x%x, right = 0x%x\n",
// y->key, (int)(y->p), (int)(y->left), (int)(y->right));
// if (y->p) {
// printf ("p = %d, ", y->p->key);
// }
// if (y->left) {
// printf ("left = %d, ", y->left->key);
// }
// if (y->right) {
// printf ("right = %d, ", y->right->key);
// }
// printf ("\n");
// } else {
// printf ("successor: not found.\n");
// }
//and y has no left childs !!
if (y->p != z) {
printf ("case 3:\n");
//replace y with y->right
//update childs manually:
//Transplant () updates parents only
Transplant (root, y, y->right);
y->right = z->right;
z->right->p = y;
}
printf ("case 4:\n");
//if y == z->right, replace z with y directly
Transplant (root, z, y);
//z has left childs, update their parents
y->left = z->left;
z->left->p = y;
}
}
void rb_tree<T>::remove(rb_vertex<T>* out_value) {
//out_value is y in Corman
// this is y in Corman
rb_vertex<T>* successor;
// this is x in Corman
rb_vertex<T>* child;
if (out_value->get_left_child() == 0 or out_value->get_right_child() == 0) {
successor = out_value;
} else {
successor = Tree_Successor(out_value);
}
if (successor->get_left_child() != 0) {
child = successor->get_left_child();
} else {
child = successor->get_right_child();
}
child->set_parent(successor->get_parent());
if (successor->get_parent() == 0) {
root = child;
} else {
if (successor == successor->get_parent()->get_left_child()) {
successor->get_parent()->set_left_child(child);
} else {
successor->get_parent()->set_right_child(child);
}
}
if (child != out_value) {
out_value->set_value(successor->get_value());
}
if (successor->get_colour() == BLACK) {
remove_fixup(child);
}
}
pNode RB_Delete(pNode root,pNode t)
{
pNode DelNode;
//{* get tthe node to delete
if((t -> left == Nil) || (t -> right == Nil) )
DelNode = t;
else
DelNode = Tree_Successor(t);
//*}
pNode PreserveNode;
if( DelNode -> left != Nil)
PreserveNode = DelNode -> left;
else
PreserveNode = DelNode -> right;
PreserveNode -> parent = DelNode -> parent; // link the DelNode's parent to PreserveNode
if( DelNode == Nil ) //if DelNode is the root
root = PreserveNode;
else {
if(DelNode == (DelNode -> parent -> left))
DelNode -> parent -> left = PreserveNode;
else
DelNode -> parent -> right = PreserveNode;
}
if(DelNode != t)
t -> key = DelNode -> key;
/*
* if the DelNode's color is black, we must fixup RBT to keep the properties of RBT.
* */
if(DelNode -> color == "BLACK")
root = RB_Delete_Fixup(root, PreserveNode);
return PreserveNode;
}
redblack_node *
redblack_node::RB_Delete(
redblack_node *T,
redblack_node* z
)
{
redblack_node *y, *x, *temp = T;
while( temp->parent != NULL )
temp = temp->parent; // point temp to the root of T
if( z == NULL )
z = new redblack_node;
if( z->left == NULL || z->right == NULL )
y = z;
else
y = static_cast<redblack_node *>(Tree_Successor( z ));
if( y == NULL )
y = new redblack_node();
if( y->left != NULL )
x = y->left;
else
x = y->right;
if( x == NULL )
x = new redblack_node;
x->parent = y->parent;
if( y->parent == NULL )
temp = x;
else if( y == y->parent->left )
y->parent->left = x;
else
y->parent->right = x;
if( y != z )
z->data = strdup( y->data );
if( strcmp( y->color, "BLACK" ) == 0 )
RB_Delete_Fixup( T, x );
return y;
}
