update: simplify typescript/LC-19

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

@@ -11,25 +11,21 @@
  */
 
 function removeNthFromEnd(head: ListNode | null, n: number): ListNode | null {
-  let dummyList: ListNode = new ListNode(0)
-  dummyList.next = head
-  let count: number = 0
-  let first: ListNode = dummyList
-  let second: ListNode = dummyList
-
-  while (count < n) {
-    second = second.next
-    count++
-  }
-  if (second === null) {
-    dummyList.val = dummyList.next.val
-    dummyList.next = dummyList.next.next
-  }
-  while (second.next !== null) {
-    second = second.next
-    first = first.next
-  }
-  first.next = first.next.next
-
-  return dummyList.next
-}
+    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
+};