public void InsertIntoBST_2()
        {
            var solution = new _0701_InsertIntoABinarySearchTree();
            var result   = solution.InsertIntoBST(null, 5);

            AssertHelper.AssertTree(new int?[] { 5 }, result);
        }
        public void InsertIntoBST_1()
        {
            var root = TestHelper.GenerateTree(new int?[] { 4, 2, 7, 1, 3 });

            var solution = new _0701_InsertIntoABinarySearchTree();
            var result   = solution.InsertIntoBST(root, 5);

            AssertHelper.AssertTree(new int?[] { 4, 2, 7, 1, 3, 5 }, result);
        }