leetcode---148.排序链表

class Solution:
    def sortList(self, head: Optional[ListNode]) -> Optional[ListNode]:
        l = []
        node = head
        while node:
            l.append(node.val)
            node = node.next
        l.sort()
        node = head
        for i in l:
            node.val = i
            node = node.next
        return head