Detect a Linked List Cycle

Problem

Given node values and the index the tail connects to (-1 for none), decide whether a cycle exists.

Examples

Example 1

Input: {"values":[3,2,0,-4],"pos":1}

Output: true

Example 2

Input: {"values":[1,2,3],"pos":-1}

Output: false

Input and output use JSON-compatible values. For linked-list and tree questions, arrays represent the node structure as described above. Your code should implement solve(input).

Write your solutionImplement solve(input). Your draft is saved in this browser.

Compiler

How to solve Detect a Linked List Cycle

Given node values and the index the tail connects to (-1 for none), decide whether a cycle exists. Try the slow and fast pointer technique. The reference implementation illustrates this approach; check the example and edge cases.

Time and space complexity

O(n) time and O(n) space to construct nodes from the JSON input.

Practise and improve

Choose JavaScript, TypeScript or Python, complete the starter code, then select Run Tests. Request a hint when you need guidance, or choose View solution and confirm if you would like to study the reference implementation.