1. # Definition for singly-linked list.
    2. # class ListNode:
    3. #     def __init__(self, x):
    4. #         self.val = x
    5. #         self.next = None
    7. class Solution:
    8.     def removeNthFromEnd(self, head: ListNode, n: int) -> ListNode:
    9.         dummy = ListNode(0)
    10.         dummy.next = head
    11.         pre, cur = dummy, dummy
    13.         for _ in range(n):
    14.             pre = pre.next
    16.         while pre.next is not None:
    17.             pre = pre.next
    18.             cur = cur.next
    20.         cur.next = cur.next.next if cur.next is not None else None
    22.         return dummy.next
    1. # Definition for singly-linked list.
    2. # class ListNode:
    3. #     def __init__(self, x):
    4. #         self.val = x
    5. #         self.next = None
    7. class Solution:
    8.     def getKthFromEnd(self, head: ListNode, k: int) -> ListNode:
    9.         if head.next is None or k == 0:
    10.             return head
    12.         i = 0
    13.         pre = cur = head
    14.         while pre is not None:
    15.             if k > i:
    16.                 i += 1
    17.                 pre = pre.next
    18.             else:
    19.                 pre = pre.next
    20.                 cur = cur.next
    21.         return cur if k == i else None