题解 | #反转链表#

#coding:utf-8
# 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
#
class Solution:
    def ReverseList(self , head ):
        # write code here
        ##init
        if head == None:
            return head
        if head.next == None:
            return head
        cur = head
        next_nd = cur.next
        prev = None
        ##process
        while cur != None:
            next_nd = cur.next #核心要点：一定要先定义next_node
            cur.next = prev
            prev = cur
            cur = next_nd
        #print ("Cur: ", cur.val)
        #print ("Cur next: ", cur.next)
        #print ("Prev: ", prev.val)
        
        return prev