給你連結串列的頭結點 head ，請將其按 升序 排列並返回 排序後的連結串列 。

list對應的歸併排序

def sortList(nums):
    n = len(nums)
    if n < 2:
        return nums
    mid=n//2
    left=merge(nums[:mid])
    right=merge(nums[mid:])
    
    ans=[]
    i = j = 0
    while i < len(left) and j < len(right):
        if left[i]<right[
 
j]:
            ans.append(left[i])
            i += 1
        else:
            ans.append(right[j])
            j+=1
    if i == len(left):
        ans.extend(right[j:])
    else:
        ans.extend(left[i:])
    return ans

用排序演算法的歸併演算法

class ListNode:
	def __init__(self,val=0,next=None):
		self.val=
 
val
		self.next=next
def sortList(self, head: ListNode) -> ListNode:
	if not head or not head.next:
		return head
	slow=head
	fast=head.next
	while fast and fast.next:
		slow=sloe.next
		fast=fast.next.next
	mid=slow.next
	slow.next=None
	left=self.sortList(head)
	right=self.sortList(mid)
	p=ans=
 
ListNode()
	while left and right:
		if left.val<right.val:
			p.next=left
			left=left.next
		else:
			p.next=right
			right=right.next
		p=p.next
	p.next=left if left else right
	return ans.next