题目:

题解:
            
            
              python
              
              
            
          
          # Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def reverseList(self, head: Optional[ListNode]) -> Optional[ListNode]:
        newHead = ListNode(0)
        newHead.next = None
        h = head
        while h:
            cur = ListNode(h.val)
            cur.next = newHead.next
            newHead.next = cur
            h = h.next
        
        return newHead.next