I'm having the hardest time trying to figure out how to balance an AVL tree for my class. I've got it inserting with this:
Node* Tree::insert(int d)
{
cout << "base insert\t" << d << endl;
if (head == NULL)
return (head = new Node(d));
else
return insert(head, d);
}
Node* Tree::insert(Node*& current, int d)
{
cout << "insert\t" << d << endl;
if (current == NULL)
current = new Node(d);
else if (d < current->data) {
insert(current->lchild, d);
if (height(current->lchild) - height(current->rchild)) {
if (d < current->lchild->getData())
rotateLeftOnce(current);
else
rotateLeftTwice(current);
}
}
else if (d > current->getData()) {
insert(current->rchild, d);
if (height(current->rchild) - height(current->lchild)) {
if (d > current->rchild->getData())
rotateRightOnce(current);
else
rotateRightTwice(current);
}
}
return current;
}
My plan was to have the calls to balance() check to see if the tree needs balancing and then balance as needed. The trouble is, I can't even figure out how to traverse the tree to find the correct unbalanced node. I know how to traverse the tree recursively, but I can't seem to translate that algorithm into finding the lowest unbalanced node. I'm also having trouble writing an iterative algorithm. Any help would be appreciated. :)