Absolute linked list sorting

'''
Logic:
 if number is positive,then no change
 else number will be in left side of head node and head node will be updated.
'''
class Node:

    def __init__(self, data):  # data -> value stored in node
        self.data = data
        self.next = None


class Solution:
    def sortList(self, head):
        if not head:
            return head

        prev, cur = head, head.next

        while cur:
            if cur.data < 0:
                prev.next = cur.next
                cur.next = head
                head = cur
                cur = prev.next
            else:
                prev, cur = cur, cur.next

        return head