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);
}
