Reverse a Linked List Problem Statement

Given a singly linked list of integers. Your task is to return the head of the reversed linked list.

Example:

Input:

The given linked list is 1 -> 2 -> 3 -> 4 -> NULL.

Output:

The reversed linked list is 4 -> 3 -> 2 -> 1 -> NULL and the head of the reversed linked list will be 4.

Explanation:

Reverse the given linked list to obtain the output.

Constraints:

• 1 ≤ T ≤ 5
• 0 ≤ L ≤ 10^5
• 1 ≤ data ≤ 10^9 and data ≠ -1

Time Limit: 1 sec

Follow Up:

Can you solve this problem in O(N) time and O(1) space complexity?

Note:

You do not need to print anything; just implement the given function.