Find the k-th Node from the End of a Linked List

Given the head node of a singly linked list and an integer 'k', this problem requires you to determine the value at the k-th node from the end of the linked list.

Example:

For a given linked list image, if k=2, the value at the second node from the end is 12.

Input:

The first line of the input contains an integer T representing the number of test cases.
For each test case, the first line contains integers denoting the nodes of the linked list, ending with -1 to signify the end of the list.
The second line contains an integer k.

Output:

For each test case, return a pointer to the node at the k-th position from the end of the linked list.

Constraints:

• 1 <= T <= 50
• 0 <= N <= 10^5
• -10^9 <= data <= 10^9
• 1 <= k <= N
• node->data ≠ -1

Note:

1. You don't need to handle the input. It's managed already. Simply implement the function to return a pointer to the k-th node from the end of the list.
2. It is guaranteed that k <= the size of the linked list.