Add #0141 Linked List Cycle

Author: dgper13

#0141 Linked List Cycle.py

@@ -0,0 +1,29 @@
+from typing import Optional
+
+class ListNode:
+    def __init__(self, x):
+        self.val = x
+        self.next = None
+
+class Solution:
+    def hasCycle(self, head: Optional[ListNode]) -> bool:
+        """
+        Detect if a linked list has a cycle in it.
+
+        Parameters:
+        head (Optional[ListNode]): The head of the singly linked list.
+
+        Returns:
+        bool: True if there is a cycle in the linked list, False otherwise.
+        """
+        slow = head
+        fast = head
+
+        while fast and fast.next:
+            slow = slow.next       # Move slow pointer by one step
+            fast = fast.next.next  # Move fast pointer by two steps
+
+            if slow == fast:       # Cycle detected if slow and fast pointers meet
+                return True
+
+        return False               # No cycle found