Simply further

Further simplify solution, this also matches the python solution shown in the video.

typescript/19-Remove-Nth-Node-From-End-of-List.ts

@@ -11,26 +11,21 @@
  */
 
 function removeNthFromEnd(head: ListNode | null, n: number): ListNode | null {
- let runner = head;
- let c = 0;
-
- while (c != n && runner != null) {
- c++;
- runner = runner.next;
- }
-
- if (runner == null) {
- return head.next;
- }
-
- let tail = head;
-
- while (runner.next != null) {
- runner = runner.next;
- tail = tail.next;
- }
-
- tail.next = tail.next.next;
-
- return head;
-}
+ let dummy: ListNode = new ListNode(0, head)
+ let left = dummy
+ let right = head
+
+ while (n > 0) {
+ right = right.next
+ n -= 1
+ }
+
+ while (right) {
+ left = left.next
+ right = right.next
+ }
+
+ // delete
+ left.next = left.next.next
+ return dummy.next
+};