Reorder Linked List

Problem

Reorder nodes as first, last, second, second-last, and so on.

Examples

Example 1

Input: [1,2,3,4,5]

Output: [1,5,2,4,3]

Example 2

Input: [1,2,3,4]

Output: [1,4,2,3]

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 Reorder Linked List

Reorder nodes as first, last, second, second-last, and so on. Find the middle, reverse the second half, then interleave. The reference implementation illustrates this approach; check the example and edge cases.

Time and space complexity

O(n) time, O(1) auxiliary space using linked-list operations.

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.