Lc222_翻转二叉树

    /**
     *
     * 反转二叉树 实际上就是反转每个节点下的叶子节点
     * @param root
     * @return
     */
    public TreeNode invertTree(TreeNode root) {
        if(root == null) {
            return null;
        }
        TreeNode left = invertTree(root.left);
        TreeNode right = invertTree(root.right);
        root.left = right;
        root.right = left;
        return root;
    }