LeetCode 19 two pointer solution

19_remove_nth_node_from_end_of_list.py

from typing import Optional


class ListNode:
    def __init__(self, val=0, next=None):
        self.val = val
        self.next = next


class Solution:
    def removeNthFromEnd(self, head: Optional[ListNode], n: int) -> Optional[ListNode]:
        """Remove the nth from the last node.

        Args:
            head (Optional[ListNode]): Head of list
            n (int): Node to remove

        Returns:
            Optional[ListNode]: Modified list
        """
        dummy = ListNode(0, head)
        left = dummy
        right = head

        node_index = 0
        while node_index < n:
            right = right.next
            node_index += 1

        while right:
            right = right.next
            left = left.next

        left.next = left.next.next

        return dummy.next