How can you find the nth node from the end of a linked list?

To find the nth node from the end of a linked list, we can use the two-pointer approach.

First, we initialize two pointers, let's call them 'first' and 'second', and set them both to point to the head of the linked list.

Next, we move the 'first' pointer n positions ahead in the linked list. If the linked list has fewer than n nodes, then it is not possible to find the nth node from the end, so we return an appropriate message or value.

After moving the 'first' pointer, we start moving both the 'first' and 'second' pointers simultaneously until the 'first' pointer reaches the end of the linked list. This can be done by advancing both pointers one node at a time.

Once the 'first' pointer reaches the end of the linked list, the 'second' pointer will be pointing to the nth node from the end. We can then return the value stored in that node or perform any desired operations on it.

Here is a step-by-step algorithm to find the nth node from the end of a linked list:

1. Initialize two pointers, 'first' and 'second', and set them both to point to the head of the linked list.
2. Move the 'first' pointer n positions ahead in the linked list. If the linked list has fewer than n nodes, return an appropriate message or value.
3. Start moving both the 'first' and 'second' pointers simultaneously until the 'first' pointer reaches the end of the linked list. Advance both pointers one node at a time.
4. Once the 'first' pointer reaches the end of the linked list, the 'second' pointer will be pointing to the nth node from the end.
5. Return the value stored in the nth node or perform any desired operations on it.

By using this approach, we can efficiently find the nth node from the end of a linked list in a single pass through the list. The time complexity of this algorithm is O(n), where n is the number of nodes in the linked list.