每天一道面试题LeetCode 206 -- 反转链表

Posted 2020-12-01 yuzhou-1su

LeetCode206 反转链表

思路

代码

#
# @lc app=leetcode.cn id=206 lang=python3
#
# [206] 反转链表
#
# https://leetcode-cn.com/problems/reverse-linked-list/description/
#
# algorithms
# Easy (61.53%)
# Likes:    624
# Dislikes: 0
# Total Accepted:    112.8K
# Total Submissions: 172.9K
# Testcase Example:  '[1,2,3,4,5]'
#
# 反转一个单链表。
# 
# 示例:
# 
# 输入: 1->2->3->4->5->NULL
# 输出: 5->4->3->2->1->NULL
# 
# 进阶:
# 你可以迭代或递归地反转链表。你能否用两种方法解决这道题？
# 
#

# @lc code=start
# 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:
        cur, prev = head, None
        while cur:
            cur.next, prev, cur = prev, cur, cur.next
        return prev
# @lc code=end