题解 | #反转链表#

想到了一个递归的思路：递归找到尾节点，每次迭代时，将下一个节点指向上一个节点

class Solution:
	def reverse_list_node(self, head: ListNode) -> ListNode
    	res = self.recursive_exchange(head, None)
        return res
        
    def recursive_exchange(head: ListNode, pre_head: ListNode) -> ListNode
    	if head:
        	post_head = head.next
            head.next = pre_head
            pre_head = head
            self.recursive_exchange(post_head, pre_head)
        else:
        	head = pre_head if pre_head else head
        return head