sol.md

1. Create a dummy node and set its next pointer to the head of the linked list.
2. Initialize two pointers, first and second, to the dummy node.
3. Advance the first pointer n + 1 nodes forward.
4. While the first pointer is not null:
   • Advance both the first and second pointers one node forward.
5. Set the next pointer of the second node to the next pointer of the second.next node.
6. Return the next pointer of the dummy node.

The time complexity of the algorithm is O(n), where n is the length of the linked list. This is because the algorithm needs to traverse the linked list twice.

The space complexity of the algorithm is O(1), since it only needs to store three pointers.