public void ZigzagLevelOrder_Null()
        {
            var solution = new _103_BinaryTreeZigzagLevelOrderTraversal();
            var result   = solution.ZigzagLevelOrder(null);

            AssertHelper.AssertList(new List <IList <int> >(), result);
        }
        public void ZigzagLevelOrder()
        {
            var solution = new _103_BinaryTreeZigzagLevelOrderTraversal();
            var result   = solution.ZigzagLevelOrder(TestHelper.GenerateTree(new int?[] { 3, 9, 20, null, null, 15, 7 }));

            AssertHelper.AssertList(new List <IList <int> >()
            {
                new List <int>()
                {
                    3
                },
                new List <int>()
                {
                    20, 9
                },
                new List <int>()
                {
                    15, 7
                }
            }, result);
        }