题目:分割链表
class Solution:
def partition(self, head: ListNode, x: int) -> ListNode:
p=less=ListNode(0)
q=more=ListNode(0)
while head:
if head.val<x:
less.next=head
less=less.next
else:
more.next=head
more=more.next
head=head.next
# 链表的最后都需要指向None,这个代表链表的结束
more.next=None
less.next=q.next
return p.next