Given the head of a singly linked list, reverse the list, and return the reversed list.
Example 1:
Input: head = [1,2,3,4,5] Output: [5,4,3,2,1] Example 2:
Input: head = [1,2] Output: [2,1] Example 3:
Input: head = [] Output: []
Constraints:
The number of nodes in the list is the range [0, 5000]. -5000 <= Node.val <= 5000
Follow up: A linked list can be reversed either iteratively or recursively. Could you implement both?