/**
* Internal method to find an item in a subtree.
*
* @param x is item to search for.
* @param t the node that roots the tree.
* @return node containing the matched item.
*/
private AvlNode find(Comparable x, AvlNode t) {
while (t != null)
if (x.compareTo(t.element) < 0) t = t.left;
else if (x.compareTo(t.element) > 0) t = t.right;
else return t; // Match
return null; // No match
}
/**
* 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;
}