Problem

Given the head of a singly linked list, reverse the list, and return the new head node. The linked list is defined as follows:

class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next

Examples

Example 1:

Input: head = [1, 2, 3, 4, 5]
Output: [5, 4, 3, 2, 1]

Example 2:

Input: head = [1, 2]
Output: [2, 1]

Constraints

• The number of nodes in the list is in the range [0, 5000].
• -5000 <= Node.val <= 5000.