solve: remove nth node from end of list

Author: sounmind

remove-nth-node-from-end-of-list/evan.js

@@ -0,0 +1,33 @@
+/**
+ * @param {ListNode} head
+ * @param {number} n
+ * @return {ListNode}
+ */
+function removeNthFromEnd(head, n) {
+  let dummy = new ListNode(0);
+  dummy.next = head;
+  let first = dummy;
+  let second = dummy;
+
+  // Move the first pointer n+1 steps ahead
+  for (let i = 0; i <= n; i++) {
+    first = first.next;
+  }
+
+  // Move both pointers until the first pointer reaches the end
+  // Second pointer will be at the (n+1)th node from the end
+  while (first !== null) {
+    first = first.next;
+    second = second.next;
+  }
+
+  // Remove the nth node from the end
+  second.next = second.next.next;
+
+  return dummy.next;
+}
+
+/**
+ * Time Complexity: O(n)
+ * Space Complexity: O(1)
+ */