Hot100: Palindrome Linked List Fast/Slow + Reverse Second Half O(1) Space ACERS Guide
Subtitle / Summary The core of palindrome validation is symmetric comparison, but a singly linked list cannot move backward. The most stable engineering template is: find middle -> reverse second half in-place -> compare -> reverse back to restore. Reading time: 10-14 min Tags: Hot100, linked list, fast slow pointers, in-place reverse SEO keywords: Palindrome Linked List, fast slow pointers, reverse second half, O(1) space, LeetCode 234 Meta description: O(n)/O(1) palindrome check for singly linked list with middle detection, second-half reversal, comparison, and full structure restoration. Target Readers Hot100 learners who want to master the “middle + reverse” linked-list combo Developers who frequently solve palindrome/symmetry interview questions Engineers who care about low extra memory and non-destructive checks Background / Motivation For arrays, palindrome check is easy with two pointers from both ends. For singly linked lists, you can only move forward via next, so symmetric comparison is not direct. ...