# Definition for singly-linked list.
# class ListNode:
# def __init__(self, x):
# self.val = x
# self.next = None
class Solution:
def reverseList(self, head: ListNode) -> ListNode:
if not head:
return None
p = ListNode(head.val)
p.next = None
while head.next != None:
head = head.next
tmp = ListNode(head.val)
tmp.next = p
p = tmp
return p