/**
* Ensures that this BinarySearchTree object contains a specified element. The worstTime(n) is
* O(n) and averageTime(n) is O(log n).
*
* @param element - the element whose presence is ensured in this BinarySearchTree object.
* @return true - if this BinarySearchTree object changed as a result of this method call (that
* is, if element was actually inserted); otherwise, return false.
* @throws ClassCastException - if element cannot be compared to the elements already in this
* BinarySearchTree object.
* @throws NullPointerException - if element is null.
*/
public boolean add(E element) {
if (root == null) {
if (element == null) throw new NullPointerException();
root = new Entry<E>(element, null);
size++;
return true;
} // empty tree
else {
Entry<E> temp = root;
int comp;
while (true) {
comp = ((Comparable) element).compareTo(temp.element);
if (comp == 0) return false;
if (comp < 0)
if (temp.left != null) temp = temp.left;
else {
temp.left = new Entry<E>(element, temp);
size++;
return true;
} // temp.left == null
else if (temp.right != null) temp = temp.right;
else {
temp.right = new Entry<E>(element, temp);
size++;
return true;
} // temp.right == null
} // while
} // root not null
} // method add
protected Entry<E> copy(Entry<? extends E> p, Entry<E> parent) {
if (p != null) {
Entry<E> q = new Entry<E>(p.element, parent);
q.left = copy(p.left, q);
q.right = copy(p.right, q);
return q;
} // if
return null;
} // method copy