python leetcode 206. Reverse Linked List 92. Reverse Linked List II

最新推荐文章于 2020-05-29 06:24:42 发布

原创最新推荐文章于 2020-05-29 06:24:42 发布 · 666 阅读

0 ·

CC 4.0 BY-SA版权

文章标签：

#python #leetcode

python 同时被 2 个专栏收录

263 篇文章

订阅专栏

leetcode

221 篇文章

订阅专栏

206. Reverse Linked List

class Solution(object):
    def reverseList(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        p = None
        while head:
            tmp = head
            head = head.next 
            tmp.next = p 
            p = tmp
        return p

Reverse Linked List II

class Solution(object):
    def reverseBetween(self, head, m, n):
        """
        :type head: ListNode
        :type m: int
        :type n: int
        :rtype: ListNode
        """
        if not head or not head.next:
            return head 
        res=ListNode(0)
        res.next=head
        p=res 
        count=m
        while count>1:
            p=p.next
            count-=1
        #要转换的开头是q,长度为n-m+1,保存p，q
        q=p.next
        p.next=None
        count=n-m+1
        n1=q
        n2=n1.next
        q.next=None
        #三指针逆序,头n1，尾巴q，下一个节点n2
        while count>1:
            n3=n2.next
            n2.next=n1
            n1=n2
            n2=n3 
            count-=1 
        p.next=n1 
        q.next=n2
        return res.next