<p>Given the <code>head</code> of a linked list, remove the <code>n<sup>th</sup></code> node from the end of the list and return its head.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/10/03/remove_ex1.jpg" style="width: 542px; height: 222px;" />
<pre>
<strong>Input:</strong> head = [1,2,3,4,5], n = 2
<strong>Output:</strong> [1,2,3,5]
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> head = [1], n = 1
<strong>Output:</strong> []
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> head = [1,2], n = 1
<strong>Output:</strong> [1]
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The number of nodes in the list is <code>sz</code>.</li>
	<li><code>1 &lt;= sz &lt;= 30</code></li>
	<li><code>0 &lt;= Node.val &lt;= 100</code></li>
	<li><code>1 &lt;= n &lt;= sz</code></li>
</ul>

<p>&nbsp;</p>
<p><strong>Follow up:</strong> Could you do this in one pass?</p>

# Definition for singly-linked list.
# class ListNode:
#     def __init__(self, val=0, next=None):
#         self.val = val
#         self.next = next
class Solution:
    # Neetcode:

    def removeNthFromEnd(self, head: Optional[ListNode], n: int) -> Optional[ListNode]:
        dummy = ListNode(0, head) # create dummy node before head 
        left = dummy 
        right = head 
        while n > 0 and right: 
            right = right.next 
            n -= 1
        
        while right: # shift l, and r until right goes to the end of the list 
            left = left.next
            right = right.next
        
        # delete the node 
        left.next = left.next.next 

        return dummy.next # updated head of the list (do not include dummy in output)



    # MY SOLUTION - IT WORKS!!!
    # def removeNthFromEnd(self, head: Optional[ListNode], n: int) -> Optional[ListNode]:
    #     length = 0
    #     current = head
    #     while current:
    #         length += 1 
    #         current = current.next 
    #     print("Check we've finished: ", current)
    #     print("Length is: ", length)

    #     toDeleteNext = length - n
    #     print("toGoFromStart: ", toDeleteNext)
        
    #     if toDeleteNext == 0:
    #         return head.next 
    
    #     current = head
    #     for i in range(1, toDeleteNext):
    #         print("i is: ", i)
    #         current = current.next
    #         print("val is: ", current.val)
        
    #     print("Now the one before the one to remove: ", current.val)
        

    #     toRemove = current.next 
    #     print("To Remove node: ", toRemove.val)
    #     toConnect = toRemove.next 

    #     current.next = toConnect 

    #     return head
        
16300