Hot100: Reverse Linked List II Dummy Node + Head-Insertion ACERS Guide
Subtitle / Summary Reverse Linked List II is not about full-list reversal; it is about reversing a strict middle interval while preserving both outer connections. This ACERS guide explains the dummy-node anchor, head-insertion loop, and boundary-safe implementation. Reading time: 12-15 min Tags: Hot100, linked list, sublist reversal, dummy node SEO keywords: Reverse Linked List II, sublist reversal, dummy node, head insertion, LeetCode 92, Hot100 Meta description: In-place sublist reversal with dummy node + head insertion in O(n)/O(1), with correctness intuition, pitfalls, and runnable multi-language code. Target Readers Hot100 learners who already know 206 and want the interval version Developers who often fail at linked-list boundary handling (left = 1, right = n) Engineers building reusable pointer-rewiring templates Background / Motivation LeetCode 206 reverses the whole list. LeetCode 92 asks for a stricter operation: ...