2046. Sort Linked List Already Sorted Using Absolute Values

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# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def sortLinkedList(self, head: Optional[ListNode]) -> Optional[ListNode]:

        start, end = head, head

        node = head

        while node.next:
            if node.next.val > 0:
                end = node.next
                node = node.next
            else:
                neg = node.next
                end.next = neg.next
                neg.next = start
                start = neg

                node = end

        return start