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. A - Algorithm (Problem and Algorithm) Problem Restatement Given the head of a singly linked list and two integers left and right (1 <= left <= right <= n), reverse the nodes from position left to right, and return the new head. ...