题解 | #反转链表#

# -*- coding:utf-8 -*-
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
class Solution:
    # 返回ListNode
    def ReverseList(self, pHead):
        # write code here
        if pHead == None:
            return pHead
        if pHead.next == None:
            return pHead
        pre = None
        now = pHead
        nxt = now.next
        
        while True:
            if now:
                now.next = pre
                
                pre = now
                now = nxt
                if now:
                    nxt = now.next
                else:
                    break
        return pre