public void SortedArrayToBSTTest()
        {
            var solution = new _108_ConvertSortedArrayToBinarySearchTree();
            var result   = solution.SortedArrayToBST(new int[] { -10, -3, 0, 5, 9 });

            AssertHelper.AssertTree(new int?[] { 0, -3, 9, -10, null, 5 }, result);
        }
        public void SortedArrayToBSTTest_Empty()
        {
            var solution = new _108_ConvertSortedArrayToBinarySearchTree();
            var result   = solution.SortedArrayToBST(new int[] { });

            Assert.IsNull(result);
        }