013-partition_data.py

from linked_list import LinkedList


class MyLinkedList(LinkedList):

    def partition(self, data):
        if self.head is None:
            return
        left = MyLinkedList(None)
        right = MyLinkedList(None)
        curr = self.head

        # Build the left and right lists
        while curr is not None:
            if curr.data < data:
                left.append(curr.data)
            elif curr.data == data:
                right.insert_to_front(curr.data)
            else:
                right.append(curr.data)
            curr = curr.next
        curr_left = left.head
        if curr_left is None:
            return right
        else:
            # Merge the two lists
            while curr_left.next is not None:
                curr_left = curr_left.next
            curr_left.next = right.head
            return left