🔥 Linked List Cycle

Author: maddhruv

README.md

@@ -30,3 +30,4 @@ Solutions of LeetCode Blind 75 Problems in JavaScript
 | [Longest Consecutive Sequence](./longest-consecutive-sequence.js)                 | <img src="https://img.shields.io/badge/-Medium-orange" /> | `Array`, `HashTable`                               | [:link:](https://leetcode.com/problems/longest-consecutive-sequence/)         |
 | [Insert Interval](./insert-interval.js)                                           | <img src="https://img.shields.io/badge/-Medium-orange" /> | `Array`                                            | [:link:](https://leetcode.com/problems/insert-interval/)                      |
 | [Reverse Linked List](./reverse-linked-list.js)                                   | <img src="https://img.shields.io/badge/-Easy-green" />    | `Linked List`                                      | [:link:](https://leetcode.com/problems/reverse-linked-list/)                  |
+| [Linked List Cycle](./linked-list-cycle.js)                                       | <img src="https://img.shields.io/badge/-Easy-green" />    | `Linked List`, `Hash Table`, `Two Pointers`        | [:link:](https://leetcode.com/problems/linked-list-cycle/)                    |

linked-list-cycle.js

@@ -0,0 +1,30 @@
+// Two Pointers
+const hasCycle = (head) => {
+  let slow = (fast = head);
+
+  while (fast && fast.next) {
+    slow = slow.next;
+    fast = fast.next.next;
+
+    if (slow == fast) return true;
+  }
+
+  return false;
+};
+
+// Using Hash Map/Set
+const hasCycle2 = (head) => {
+  let visited = new Set();
+
+  let current = head;
+
+  if (!current) return false;
+
+  while (current) {
+    if (visited.has(current)) return true;
+    visited.add(current);
+    current = current.next;
+  }
+
+  return false;
+};