The interviewer probably learned the trick with two pointers and wanted to see you implement it, for no real reason. This question, just like it's well-known si

The interviewer probably learned the trick with two pointers and wanted to see you implement it, for no real reason. This question, just like it's well-known sibling question "check if the linked list has a loop", has absolutely no practical applicability; no one will ever want to find k-th element from the end of the linked list, it's just not the right data structure for this kind of task: it's better to use an array or a double linked list if you need to do this operation often.