LeetCode:206. Reverse Linked List

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题目描述

Reverse a singly linked list.

Example:

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Input: 1->2->3->4->5->NULL
Output: 5->4->3->2->1->NULL

用一个虚的头节点（如下的start节点）可以简化代码。

代码实现

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class Solution:
    def reverseList(self, head: 'ListNode') -> 'ListNode':
        if head == None:
            return head
        start = ListNode(0)
        start.next = head
        tmp = head
        last = start
        while tmp != None:
            nextTmp = tmp.next
            tmp.next = last
            last = tmp
            tmp = nextTmp

        head.next = None
        return last