Add remove-nth-node-from-end-of-list solution

remove-nth-node-from-end-of-list/Jeehay28.js

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+// 🚀 Optimized Approach: Two-Pointer Method (One-Pass)
+// ✅ Time Complexity: O(N), where N is the number of nodes
+// ✅ Space Complexity: O(1)
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+/**
+ * @param {ListNode} head
+ * @param {number} n
+ * @return {ListNode}
+ */
+var removeNthFromEnd = function (head, n) {
+  let dummy = new ListNode(0, head);
+  let fast = dummy;
+  let slow = dummy;
+
+  for (let i = 0; i <= n; i++) {
+    fast = fast.next;
+  }
+
+  while (fast) {
+    fast = fast.next;
+    slow = slow.next;
+  }
+
+  slow.next = slow.next.next;
+
+  return dummy.next;
+};
+
+// ✅ Time Complexity: O(N), where N is the number of nodes
+// ✅ Space Complexity: O(1)
+
+/**
+ * Definition for singly-linked list.
+ * function ListNode(val, next) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.next = (next===undefined ? null : next)
+ * }
+ */
+/**
+ * @param {ListNode} head
+ * @param {number} n
+ * @return {ListNode}
+ */
+// var removeNthFromEnd = function (head, n) {
+//   let length = 0;
+
+//   let node = head;
+
+//   // Compute the length of the linked list
+//   while (node) {
+//     length += 1;
+//     node = node.next;
+//   }
+
+//   // Create a dummy node pointing to head (helps handle edge cases)
+//   let dummy = new ListNode(0, head);
+//   node = dummy;
+
+//   // Move to the node just before the one to be removed
+//   for (let i = 0; i < length - n; i++) {
+//     node = node.next;
+//   }
+
+//   // Remove the nth node from the end by updating the next pointer
+//   node.next = node.next.next;
+
+//   // Return the modified linked list (excluding the dummy node)
+//   return dummy.next;
+// };