题解 | #反转链表#

# 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: ListNode) -> ListNode:
        # write code here
        prev=None
        curr=head
        #改变指针方向.val\.next
        while curr:
            next_c=curr.next
            curr.next=prev
            prev=curr
            curr=next_c
        #指定新的头节点
        head=prev
        return head