public class BinaryTree implements Tree {
	//Data
	protected TreeNode root;

	//Constructors
  	public BinaryTree() { this(null); }
  	public BinaryTree(TreeNode n) { root = n; }
	
	//Access methods
	public TreeNode getRoot() { return root; }
	
	public BinaryTree getLeftSubtree() {
		return isEmpty() ? null : new BinaryTree(root.left);
	}
	
	public BinaryTree getRightSubtree() {
		return isEmpty() ? null : new BinaryTree(root.right);
	}
	
  	//Tree methods
  	public void add(Object element) {
  		if(isEmpty()) root = new TreeNode(element);
    	else {
      		int w = (int)(100.0 * Math.random()) % 2;
      		if( w == 0)
           		if(root.left == null) root.left = new TreeNode(element);
           		else getLeftSubtree().add(element);
      		else
           		if(root.right == null) root.right = new TreeNode(element);
           		else getRightSubtree().add(element);
    	}
  	}
  	
  	public Object remove(Object element) {
  		throw new UnsupportedOperationException();
  	}
  	
  	public boolean contains(Object element) {
  		if(isEmpty()) return false;
  		if(root.data.equals(element)) return true;
  		return getLeftSubtree().contains(element) ?
  						true : getRightSubtree().contains(element);
  	}
    
  	public boolean isEmpty() { return root == null; }

	public int size() {
  		throw new UnsupportedOperationException();
 	}
 	
	public int height() {
		return isEmpty() ? 
			-1 : Math.max(getLeftSubtree().height(),getRightSubtree().height()) + 1;

	}
	
	public int numberOfLiefs() {
		throw new UnsupportedOperationException();
	}
	
	public void clear() { root = null; }
			
	public java.util.Iterator iterator() {
		return new BTreeInorderIterator(this); 
	}
	public java.util.Iterator treeInorderIterator() {
		return new BTreeInorderIterator(this);
	}
	public java.util.Iterator treePreorderIterator() {
		throw new UnsupportedOperationException();
	}
	public java.util.Iterator treePostorderIterator() {
		throw new UnsupportedOperationException();
	}
  	public java.util.Iterator treeBreadthFirstIterator() {
  		return new BTreeBreadthFirstIterator(this);
  	}
	
  	public Object clone() { throw new UnsupportedOperationException(); }
    public String toString() { throw new UnsupportedOperationException(); }
}