19. Remove Nth Node From End of List

https://leetcode.com/problems/remove-nth-node-from-end-of-list

Python

(First Run)

class Solution:
    def removeNthFromEnd(self, head: Optional[ListNode], n: int) -> Optional[ListNode]:
        dummy = ListNode(val=-1, next=head)
        cur_1 = dummy
        cur_2 = dummy

        for i in range(0, n+1):
            cur_1 = cur_1.next

        while cur_1 is not None:
            cur_1 = cur_1.next
            cur_2 = cur_2.next

        cur_2.next = cur_2.next.next
        return dummy.next

(Second Run)

class Solution:
    def removeNthFromEnd(self, head: Optional[ListNode], n: int) -> Optional[ListNode]:
        cur = head
        length = 0

        while cur:
            cur = cur.next
            length += 1

        dummy = ListNode(val=-1, next=head)
        cur = dummy
        for i in range(length-n):
            cur = cur.next

        cur.next = cur.next.next if cur.next else cur.next
        return dummy.next

Javascript

var removeNthFromEnd = function(head, n) {
    let prevNode = null;
    let currNode = head;
    
    while (currNode !== null) {
      const nextNode = currNode.next;
      currNode.next = prevNode;
      
      prevNode = currNode;
      currNode = nextNode;
    }
  
  
    currNode = new ListNode(0, prevNode);
    prevNode = null;
    let count = 0
  
    while (currNode !== null) {
      const nextNode = n - 1 === count ? currNode.next.next : currNode.next;
      currNode.next = prevNode;
      
      prevNode = count === 0 ? prevNode : currNode;
      currNode = nextNode;
      
      count++;
    }
  
    return prevNode;
};