Merge pull request #1915 from Lustellz/main

[Lustellz] WEEK 09 solution

Author: TonyKim9401

linked-list-cycle/Lustellz.ts

@@ -0,0 +1,29 @@
+/**
+ * Definition for singly-linked list.
+ * class ListNode {
+ *     val: number
+ *     next: ListNode | null
+ *     constructor(val?: number, next?: ListNode | null) {
+ *         this.val = (val===undefined ? 0 : val)
+ *         this.next = (next===undefined ? null : next)
+ *     }
+ * }
+ */
+
+// Runtime: 49ms
+// Memory: 56.94MB
+
+function hasCycle(head: ListNode | null): boolean {
+  let fast: ListNode = head;
+  let slow: ListNode = head;
+
+  while (fast && fast.next) {
+      fast = fast.next.next;
+      slow = slow!.next;
+
+      if (fast === slow) {
+          return true;
+      }
+  }
+  return false;
+}