How to find nth element from the end of a singly linked list?

Question

The following function is trying to find the nth to last element of a singly linked list.

For example:

If the elements are

Answer 1

Depending of the memory cost tolerance (O(k) in this solution) we could allocate an array of pointers of length k, and populate it with the nodes as a circular array while traversing the linked list.

When we finish traversing the linked list, the first element of the array (just be sure to calculate the 0-index properly as it's a circular array) we'll have the answer.

If the first element of the array is null, there's no solution to our problem.