From 41b70c839db7731d2a51eba9e17311b6127e9340 Mon Sep 17 00:00:00 2001
From: Yuseok Jo <yuseok89@gmail.com>
Date: Wed, 19 Aug 2026 23:43:58 +0900
Subject: [PATCH] linked list cycle solution

---
 linked-list-cycle/yuseok89.py | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)
 create mode 100644 linked-list-cycle/yuseok89.py

diff --git a/linked-list-cycle/yuseok89.py b/linked-list-cycle/yuseok89.py
new file mode 100644
index 0000000000..6d956e6910
--- /dev/null
+++ b/linked-list-cycle/yuseok89.py
@@ -0,0 +1,22 @@
+# TC: O(N)
+# SC: O(1)
+# Definition for singly-linked list.
+# class ListNode:
+#     def __init__(self, x):
+#         self.val = x
+#         self.next = None
+
+class Solution:
+    def hasCycle(self, head: Optional[ListNode]) -> bool:
+        if not head or not head.next:
+            return False
+
+        slow, fast = head, head.next
+        while slow != fast:
+            if not fast or not fast.next:
+                return False
+
+            slow, fast = slow.next, fast.next.next
+
+        return True
+