翻转单链表

reverse_linked_list.py

# -*- 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 is None or pHead.next is None:
            return pHead
        pre = None
        cur = pHead
        new_head = cur
        while cur:
            new_head = cur
            next = cur.next
            cur.next = pre
            pre = cur
            cur = next
        return new_head