leetcode/python/0148-sort-list.py at main · ColstonBod-oy/leetcode · GitHub

Name: leetcode/python/0148-sort-list.py at main · ColstonBod-oy/leetcode · GitHub
Rating: 4.9 (6908 reviews)
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classSolution:
defsortList(self, head: Optional[ListNode]) ->Optional[ListNode]:
ifnotheadornothead.next:
returnhead

mid=self.get_mid(head)
left, right=self.sortList(head), self.sortList(mid)

returnself.merge_two_sorted(left, right)


defmerge_two_sorted(self, list1: Optional[ListNode], list2: Optional[ListNode]) ->Optional[ListNode]:
ifnotlist1:
returnlist2

ifnotlist2:
returnlist1

sentinel=ListNode()
prev=sentinel
whilelist1andlist2:
iflist1.val<list2.val:
prev.next=list1
list1=list1.next
else:
prev.next=list2
list2=list2.next
prev=prev.next

iflist1:
prev.next=list1
else:
prev.next=list2

returnsentinel.next


defget_mid(self, head: Optional[ListNode]) ->Optional[ListNode]:
mid_prev=None
whileheadandhead.next:
mid_prev=mid_prev.nextifmid_prevelsehead
head=head.next.next

mid=mid_prev.next
mid_prev.next=None

returnmid