Detect Loop or Cycle in Linked List

In this video, we explore how to detect a loop or cycle in a linked list. A linked list loop occurs when the last node's next pointer points back to any of the previous nodes, causing an infinite cycle. We present two solutions to efficiently detect such loops: the Naive Approach using a hash set and Floyd's Cycle-Finding Algorithm (also known as the Tortoise and Hare Algorithm). The Naive Approach uses an unordered hash set to store each node as we traverse the list, checking for duplicates. If a node is revisited, it indicates a cycle. This method has a time complexity of O(n) and space complexity of O(n).

On the other hand, Floyd’s Cycle-Finding Algorithm offers an optimized solution by using two pointers, slow and fast. The slow pointer advances one step at a time, while the fast pointer advances two steps. If there's a loop, the two pointers will meet at some point within the cycle. This approach achieves O(n) time complexity and O(1) space complexity, making it more space-efficient. This method is widely used for cycle detection due to its simplicity and efficiency.

For more details, please go through - Detect Loop or Cycle in Linked List