求二叉树的深度

@Override
	public int getHeight() {
		return this.getHeight(root);
	}

	private int getHeight(Node node) {
		if (node == null)
			return 0;// 递归结束：空树高度为0
		else {
			int i = getHeight(node.leftChild);
			int j = getHeight(node.rightChild);
			return (i < j) ? (j + 1) : (i + 1);
		}
	}
	
	public void levelOrderByStack(){
		this.levelOrderByStack(root);
	}