Given the head of a singly linked list, reverse the list, and return the reversed list.
Example 1:
Input: 1 2 3 4 5 Output: 5 4 3 2 1
Example 2:
Input: 1 2 Output: 2 1
Example 3:
Input: (empty) Output: (empty)
Constraints:
- The number of nodes in the list is in the range [0, 5000]
- -5000 ≤ Node.val ≤ 5000
Input format: A single line of space-separated integers representing the linked list nodes in order. Empty line for empty list.
Output format: A single line of space-separated integers representing the reversed linked list.