public static void rotateRight(AVLNode origRoot) {
// === Difference from rotateLeft ===
AVLNode newRoot = origRoot.left;
// Original root's left (previously new root) becomes new root's right
origRoot.left = newRoot.right;
// New root's right becomes original root
newRoot.right = origRoot;
// If original root is not root of tree
if (origRoot.parent != null) {
// Update new root's parent's link to it based on
// whether original root is left or right child
if (origRoot.parent.left.key == origRoot.key) {
origRoot.parent.left = newRoot;
} else {
origRoot.parent.right = newRoot;
}
}
// Update new root's parent to be original root's parent
newRoot.parent = origRoot.parent;
// Update original root's parent to be new root
origRoot.parent = newRoot;
// Update heights of original and new root
newRoot.height -= 1;
origRoot.height += 1;
}
/**
* Perform a right (clockwise) rotation at <tt>x</tt>.
*
* @param x the lowest unbalanced node found in this tree.
* @return The new root of the balanced subtree.
*/
private AVLNode<E> rightRotation(AVLNode<E> x) {
AVLNode<E> newRoot = (AVLNode<E>) x.leftChild;
newRoot.parent = x.parent;
x.parent = newRoot;
x.leftChild = newRoot.rightChild;
// newRoot is guaranteed to have a left child, but
// we can't be sure it has a right child
if (newRoot.rightChild != null) {
newRoot.rightChild.parent = x;
}
newRoot.rightChild = x;
// lastly: do updates from the bottom up
updateBalanceAndHeight(x);
updateBalanceAndHeight(newRoot);
return newRoot;
}
