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
        if not head or not head.next:
            return head
        stack = []
        
        cur = head
        while cur:
            stack.append(cur)
            nxt = cur.next
            cur.next = None
            cur = nxt
        node = stack.pop()
        cur = node
        while stack:
            cur.next = stack.pop()
            cur = cur.next
        return node