public void TestBinaryTreePaths()
        {
            int?[]   nums = { 1, 2, 3, null, 5 };
            TreeNode node = TreeNode.GenerateTreeNode(nums);

            List <string> LIST = BstLeetCode.BinaryTreePaths(node);
        }
        public void TestLevelOrderBottom()
        {
            int?[]   nums     = { 3, 9, 20, null, null, 15, 7 };
            TreeNode treeNode = TreeNode.GenerateTreeNode(nums);

            BstLeetCode.LevelOrderBottom(treeNode);
        }