Remove Nth Node From End of List Program (Leetcode)

Remove Nth Node From End of List Program (Leetcode):

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?

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    def removeNthFromEnd(self, head: ListNode, n: int) -> ListNode:
        count = 1
        start = head
        last = head
        
        while count <= n:
            count += 1
            last = last.next
            
        if last == None:
            head = head.next
            return head
            
        while last.next != None:
            start = start.next
            last = last.next
            
        start.next = start.next.next
        return head