How to detect a cycle in a Linked List using Floyd's Cycle-Finding Algorithm?
Quick Revision Summary
Floyd's Cycle-Finding Algorithm (also known as the Hare and Tortoise Algorithm ) determines whether a singly linked list contains a cycle using two pointers traversing the list ...
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Model Answer & Deep-Dive Explanation
Floyd's Cycle-Finding Algorithm (also known as the Hare and Tortoise Algorithm) determines whether a singly linked list contains a cycle using two pointers traversing the list at different speeds.
Algorithm Mechanism:
- Initialize two pointers:
slowandfastat the head of the list. - Move
slowforward by 1 step (slow = slow.next). - Move
fastforward by 2 steps (fast = fast.next.next). - If the pointers ever meet (
slow === fast), a cycle exists. - If
fastorfast.nextreachesnull, the list is acyclic.
Interviewer Evaluation Points & Scoring Rubric
- 1 Analyze Time Complexity (Big O) and Space Complexity explicitly.
- 2 Address boundary cases: empty input, null pointers, single elements.
- 3 Write idiomatic, readable code with descriptive variable naming.
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