private AvlNode<T> rotateWithRightChild(AvlNode<T> k2) {
AvlNode<T> k1 = k2.right;
k2.right = k1.left;
k1.left = k2;
k2.height = Math.max(height(k2.left), height(k2.right)) + 1;
k1.height = Math.max(k2.height, height(k1.right)) + 1;
return k1;
}
/**
* Rotate binary tree node with right child. For AVL trees, this is a single rotation for case 4.
* Update heights, then return new root.
*/
private static AvlNode rotateWithRightChild(AvlNode k1) {
AvlNode k2 = k1.right;
k1.right = k2.left;
k2.left = k1;
k1.height = max(height(k1.left), height(k1.right)) + 1;
k2.height = max(height(k2.right), k1.height) + 1;
return k2;
}
/**
* Internal method to insert into a subtree.
*
* @param x the item to insert.
* @param t the node that roots the tree.
* @return the new root.
*/
private AvlNode insert(Comparable x, AvlNode t) {
if (t == null) t = new AvlNode(x, null, null);
else if (x.compareTo(t.element) < 0) {
t.left = insert(x, t.left);
if (height(t.left) - height(t.right) == 2)
if (x.compareTo(t.left.element) < 0) t = rotateWithLeftChild(t);
else t = doubleWithLeftChild(t);
} else if (x.compareTo(t.element) > 0) {
t.right = insert(x, t.right);
if (height(t.right) - height(t.left) == 2)
if (x.compareTo(t.right.element) > 0) t = rotateWithRightChild(t);
else t = doubleWithRightChild(t);
} else ; // Duplicate; do nothing
t.height = max(height(t.left), height(t.right)) + 1;
return t;
}
public AvlNode<T> insert(T x, AvlNode<T> t) {
if (t == null) return new AvlNode<>(x, null, null);
int compareResult = compare(x, t.element);
if (compareResult < 0) {
t.left = insert(x, t.left);
if (height(t.left) - height(t.right) == 2)
if (compare(x, t.left.element) < 0) t = rotateWithLeftChild(t);
else t = doubleWithLeftChild(t);
} else if (compareResult > 0) {
t.right = insert(x, t.right);
if (height(t.right) - height(t.left) == 2)
if (compare(x, t.right.element) > 0) t = rotateWithRightChild(t);
else t = doubleWithRightChild(t);
} else ;
t.height = Math.max(height(t.left), height(t.right)) + 1;
return t;
}
