Day 12: Attempt 2: 141_Linked_List_Cycle

Readme.md

@@ -50,6 +50,7 @@ Remember, the 75 Hard Challenge is about personal growth and discipline. Stay co
 - Day 11: [155. Min Stack](https://leetcode.com/problems/min-stack/)
 - Day 11: [150. Evaluate Reverse Polish Notation](https://leetcode.com/problems/evaluate-reverse-polish-notation/)
 <!-- - Day 11: [224. Basic Calculator](https://leetcode.com/problems/basic-calculator/) -->
+- Day 12: [141. Linked List Cycle](https://leetcode.com/problems/linked-list-cycle/)
 
 
 

top_interview_questions/75_hard/Linked List/141_Linked_List_Cycle.py

@@ -0,0 +1,17 @@
+from typing import Optional
+# 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:
+        tortoise = head
+        hare = head
+        while hare and hare.next:
+            tortoise = tortoise.next
+            hare = hare.next.next
+            if tortoise == hare:
+                return True
+        return False