feat: Add solution for LeetCode problem 141

Author: WhiteHyun

linked-list-cycle/WhiteHyun.swift

@@ -0,0 +1,29 @@
+//
+//  141. Linked List Cycle.swift
+//  https://leetcode.com/problems/linked-list-cycle/description/
+//  Algorithm
+//
+//  Created by 홍승현 on 2024/05/04.
+//
+
+import Foundation
+
+final class LeetCode141 {
+  func hasCycle(_ head: ListNode?) -> Bool {
+    guard head != nil, head?.next != nil
+    else {
+      return false
+    }
+
+    var tortoise = head
+    var hare = head?.next
+
+    while hare != nil, hare?.next != nil {
+      if tortoise === hare { return true }
+      tortoise = tortoise?.next
+      hare = hare?.next?.next
+    }
+
+    return false
+  }
+}