Interview Q&A / Data Structures & Algorithms
Data Structures & Algorithms interview questions
Arrays, linked lists, hashing, trees and patterns, with line-by-line code and complexity.
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- How do you detect a cycle in a linked list?
Use Floyd's tortoise and hare method. Move a slow pointer one step and a fast pointer two steps at a time. If the fast pointer reaches null, there is no cycle. If the two pointers ever meet, there is a cycle. It runs in O(n) time with O(1) extra space.
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