reverse-list.py (606B)
1 # Definition for singly-linked list. 2 # class ListNode: 3 # def __init__(self, val=0, next=None): 4 # self.val = val 5 # self.next = next 6 class Solution: 7 8 # number of nodes is min == 0 9 def reverseList(self, head: Optional[ListNode]) -> Optional[ListNode]: 10 11 if head is None or head.next is None: 12 return head 13 14 left = head 15 right = head.next 16 head.next = None 17 18 while right is not None: 19 temp = right.next 20 right.next = left 21 left = right 22 right = temp 23 24 head = left 25 26 return head