public void IsSymmetric_1() { var root = new TreeNode(1); root.left = new TreeNode(2); root.left.left = new TreeNode(3); root.left.right = new TreeNode(4); root.right = new TreeNode(2); root.right.left = new TreeNode(4); root.right.right = new TreeNode(3); var expected = true; var actual = _target.IsSymmetric(root); Assert.Equal(expected, actual); }