反转链表python3(leetcode206、剑指offer24)

剑指 Offer 24. 反转链表

定义一个函数，输入一个链表的头节点，反转该链表并输出反转后链表的头节点。

例子：

输入: 1->2->3->4->5->NULL
输出: 5->4->3->2->1->NULL

限制：0 <= 节点个数 <= 5000

# 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:
        pre, cur = None, head
        while(cur):
            temp = cur.next
            cur.next = pre
            pre = cur
            cur = temp
        return pre
        #return需要想清楚