"""

Remove Range from Linked List

Given a linked list and a start and end index, remove the elements at those

indexes (inclusive) from the list.

Reference: https://en.wikipedia.org/wiki/Linked_list

Complexity:

Time: O(n)

Space: O(1)

"""

from __future__ import annotations

def remove_range(head: object | None, start: int, end: int) -> object | None:

"""Remove nodes from index start to end (inclusive) from a linked list.

Args:

head: Head node of the linked list (must have .next attr).

start: Starting index of the range to remove.

end: Ending index of the range to remove (inclusive).

Returns:

The (possibly new) head of the modified list.

Examples:

>>> remove_range(None, 0, 0) is None

True

"""

assert start <= end

if start == 0:

for _ in range(end + 1):

if head is not None:

head = head.next

else:

current = head

for _ in range(start - 1):

current = current.next

for _ in range(end - start + 1):

if current is not None and current.next is not None:

current.next = current.next.next

return head