"""
Given a linked list, remove the n-th node from the end of list and return its head.

Example:

Given linked list: 1->2->3->4->5, and n = 2.

After removing the second node from the end, the linked list becomes 1->2->3->5.
Note:

Given n will always be valid.

Follow up:

Could you do this in one pass?
"""
def removeNthFromEnd(self, head, n):
        # Create a dummy node
        dummy = ListNode(-1)
        dummy.next = head
        
        first = dummy
        
        # Move over n nodes including dummy
        for i in range(n - 1):
            head = head.next
            
        # Increment ptrs till you reach end of list
        while head.next:
            first, head = first.next, head.next
            
        # Now first.next points to the nth node from the end
        first.next = first.next.next
        
        return dummy.next
