84. Reverse Linked List - Navigation History

You're building a browser navigation feature that needs to reverse the order of visited pages. Given a linked list of page visits, you need to reverse the list to show pages in reverse chronological order (most recent first).

Given the head of a singly linked list, reverse the list and return the new head.

Requirements

1. Basic Functionality

• Reverse the order of nodes in the linked list
• Return the new head (previously the tail)
• Handle edge cases: empty list, single node

2. Constraints

• Must reverse in-place (O(1) extra space) or with minimal space
• Cannot modify node values, only pointers
• Must handle null/empty list

Example Usage

// Input: 1 -> 2 -> 3 -> 4 -> 5 -> null
// Output: 5 -> 4 -> 3 -> 2 -> 1 -> null

const head = new ListNode(1);
head.next = new ListNode(2);
head.next.next = new ListNode(3);
// ... more nodes

const reversed = reverseList(head);
// reversed is now 3 -> 2 -> 1 -> null

Real-World Context

This problem models real-world scenarios:

• Browser history: Reverse navigation order to show recent pages first
• Undo/Redo systems: Reverse action history
• Message threads: Display messages in reverse chronological order
• Playlist reversal: Reverse song order in a playlist
• Transaction logs: Display transactions in reverse order