劍指Offer學習-面試題32:從上到下打印二叉樹(二叉樹的層次遍歷)

	/**
     * 從上到下打印二叉樹(二叉樹的層次遍歷)
     *
     * @param root
     */
    public void printFromTopToBottom(TreeNode root) {
        if (null == root) return;
        Queue<TreeNode> queue = new LinkedBlockingQueue<>();
        queue.add(root);
        while (!queue.isEmpty()) {
            int size = queue.size();
            for (int i = 0; i < size; i++) {
                TreeNode r = queue.poll();
                System.out.print(r.val);
                if (r.left != null) queue.add(r.left);
                if (r.right != null) queue.add(r.right);
            }
        }
    }