206 反转链表 python

206. 反转链表 python

• 方法一：迭代，边遍历边反转指针

# Definition for singly-linked list.
# class ListNode(object):
#     def __init__(self, x):
#         self.val = x
#         self.next = None

class Solution(object):
    def reverseList(self, head):
        """
        :type head: ListNode
        :rtype: ListNode
        """
        pre = None
        current = head
        while current:
            temp =current.next
            current.next = pre
            pre = current
            current = temp
        return pre