That said, it's actually an excellent C interview question. Combined with "write a binary tree iterator" it reliably measures one's exposure to thoughtful C programming.
This was actually one of the very first questions we used to ask during interviews at Tenable. I'm honestly kind of amazed it's now seen as some sort of tricky technique. I would think (or hope) most C programmers would see it as basic competence with pointers.
Which is exactly what Torvald's was saying. All the comments here going "that's unreadable" or "it's too clever" scare me. And I don't even consider myself some C coding rockstar (took me a bit to sort out my own mental picture of pointers).
a. loading the address of the next node. b. updating the link address when a node is deleted.
which are performed the same number of times on the same underlying data in either approach.