剑指 Offer II 024. 反转链表
# 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: ListNode) -> ListNode:
if not head:
return head
#初始化一个链表的头
returnHead = None
codeHead = head
id = 0
while codeHead:
middleHead = codeHead
codeHead = codeHead.next
middleHead.next = returnHead
returnHead = middleHead
return returnHead
