K-th Node from End of a Singly Linked List

You are given a singly linked list and an integer k. Your task is to find the k-th node from the end of the linked list.

If the linked list contains n nodes, then the k-th node from the end is the \( (n-k+1) \)th node from the beginning. If \( k > n \), print None.

The solution should use the two-pointer technique to achieve an optimal time complexity.

inputFormat

The input is given through standard input (stdin) and consists of two lines:

• The first line contains two integers n and k separated by a space, where n is the number of nodes in the linked list and k is the position from the end you need to find.
• The second line contains n space-separated integers representing the values of the nodes in the linked list. If n is 0, this line will be empty.

outputFormat

Output a single line to standard output (stdout):

• The value of the k-th node from the end. If such a node does not exist (i.e. if k is greater than the length of the list), output None.

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