Given the head of a linked list, remove the nth node from the end of the list and return its head.

Example 1:

Input: head = [1,2,3,4,5], n = 2
Output: [1,2,3,5]

Example 2:

Input: head = [1], n = 1
Output: []

Example 3:

Input: head = [1,2], n = 1
Output: [1]

Constraints:

• The number of nodes in the list is sz.
• 1 <= sz <= 30
• 0 <= Node.val <= 100
• 1 <= n <= sz

Follow up: Could you do this in one pass?

class Solution:
    def removeNthFromEnd(self, head, n):
        k = 0
        ptr = head
        while ptr.next != None:
            k = k + 1
            ptr = ptr.next
        ptr = head
        if k==n-1:
            return head.next
        else:
            for _ in range(k-n):
                ptr = ptr.next
            temp = ptr.next
            ptr.next = temp.next
        return head