筆試題---鏈表反轉

# -*- coding:utf-8 -*-
# class ListNode:
#     def __init__(self, x):
#         self.val = x
#         self.next = None
class Solution:
    # 返回ListNode
    def ReverseList(self, pHead):
        if not pHead or not pHead.next:
            return pHead
        last = None
        
        while pHead:
            temp = pHead.next
            pHead.next = last
            last = pHead
            pHead = temp
        return last
        
        # write code here

設置兩個臨時值，分別保存本節點和下一個節點，然後翻轉過來。因爲last最後表示的是原鏈表的末尾，所以返回last就好啦