@Override
protected void balance(AVLNode<T> node) {
/* Rotation cases (N = node, C = child)
* Case 1:
* N
* /
* C
* /
* O
*
* Case 2:
* N
* /
* C
* \
* O
*
* Case 3:
* N
* \
* C
* \
* O
* Case 4:
* N
* \
* C
* /
* O
*/
if (node == null) return;
int bf = node.getBalanceFactor();
if (bf == 2) {
AVLNode<T> child = node.getLeftChild();
if (child.getBalanceFactor() == -1) // Case 2
rotateLeft(child);
rotateRight(node); // Case 1
} else if (bf == -2) {
AVLNode<T> child = node.getRightChild();
if (child.getBalanceFactor() == 1) // Case 4
rotateRight(child);
rotateLeft(node); // Case 3
} else balance(node.getParent()); // Recurrsively balance parent
}
