That seems to be specific way of traversing Linked Lists (which ostensibly is different than all the other ways it has been done in textbooks, published code etc.) , not Linked Lists themselves. If you find a way of traversing a list in a way that has not been done before you can apply for a patent fort that technique. If i were to use that technique of traversing linked in a product that i sell, you could sue me. However, if came up with that particular, specific way of traversing a linked list in an interview, no patents are violated anywhere. That's just silly.