题解 | #反转链表#

# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
#
# 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
#
# 
# @param head ListNode类 
# @return ListNode类

#sys.setrecursionlimit(100000)
class Solution:
    def ReverseList(self , head: ListNode) -> ListNode:
        # write code here
        #if head is None or head.next is None:
            #return head
        '''
        newhead = self.ReverseList(head.next)
        head.next.next = head
        head.next = None
        return newhead
        '''

        '''
        if not head: return head
        res = []
        while head:
            res.append(head)
            head = head.next

        res = list(reversed(res))
        for i in range(len(res) - 1):
            res[i].next = res[i+1]

        res[-1].next = None
        #print(res[0])
        return res[0]

        '''

        temp = head
        res = []
        while temp is not None:
            res.append(temp.val)
            temp = temp.next
        res.reverse()

        temp = head
        for i in range(len(res)):
            temp.val = res[i]
            temp = temp.next

        return  head