206.reverse-linked-list.py

# @lcpr-before-debug-begin
from python3problem206 import *
from typing import *
# @lcpr-before-debug-end

#
# @lc app=leetcode.cn id=206 lang=python3
# @lcpr version=30204
#
# [206] 反转链表
#


# @lcpr-template-start

# @lcpr-template-end
# @lc code=start
# 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]:
        prev = None
        current = head
        while current:
            next_node = current.next
            current.next = prev
            prev = current
            current = next_node
        return prev
        
# @lc code=end



#
# @lcpr case=start
# [1,2,3,4,5]\n
# @lcpr case=end

# @lcpr case=start
# [1,2]\n
# @lcpr case=end

# @lcpr case=start
# [1]\n
# @lcpr case=end

#