Hot100: Reorder List In-Place Split-Reverse-Merge ACERS Guide
Subtitle / Summary Reorder List is a classic pointer choreography problem: find middle, reverse second half, then merge alternately. This guide derives the in-place O(n)/O(1) method from naive ideas and turns it into a reusable Hot100 template. Reading time: 12-15 min Tags: Hot100, linked list, in-place SEO keywords: Reorder List, split reverse merge, LeetCode 143, O(1) space Meta description: A full ACERS explanation of Reorder List with correctness intuition, boundary handling, engineering mapping, and runnable code in Python/C/C++/Go/Rust/JS. Target Readers Hot100 learners who want a stable linked-list rewire template Developers who can reverse lists but still fail on alternating merge details Engineers preparing for interviews where O(1) extra space is required Background / Motivation At first glance, this looks like simple reordering. In reality, it tests whether you can safely perform three dependent pointer operations in one workflow: ...