Sort Linked List in O(n log n) Time

Given the head of a linked list, return the list after sorting it in **ascending order**. Can you sort the linked list in `O(n log n)` time and `O(1)` memory (i.e. constant space)? ### Constraints - The number of nodes in the list is in the range `[0, 5 * 10^4]`. - `-10^5 <= Node.val <= 10^5` ### Input Format A single line of space-separated integers representing the list (or empty line). ### Output Format Print the space-separated sorted integers.