Let's solve the Reverse Linked List problem using the In-Place Manipulation of a Linked List pattern.

We'll cover the following

Statement

Constraints:

Let n be the number of nodes in a linked list.

• $1 \leq$ n $\leq 500$
• $-5000 \leq$ Node.value $\leq 5000$

Solution

So far, youâ€™ve probably brainstormed some approaches and have an idea of how to solve this problem. Letâ€™s explore some of these approaches and figure out which one to follow based on considerations, such as time complexity and any implementation constraints.

Naive approach

The naive approach to solve the reverse linked list problem is to create a new linked list by traversing the original linked list in reverse order. To do this, we can copy the nodes of the original linked list into another data structure, for example, a stack. Then, we can pop the nodes from the stack one by one, creating a new linked list with each node we pop.

This approach has a time complexity of $O(n)$, since we need to iterate through the entire original list and then iterate through the stack. However, the space complexity is also $O(n)$, since we need to store all the nodes in the data structure. This means that if the original linked list is very large, we may run into memory issues. Overall, while this approach is simple to implement, it may not be the most efficient solution for large linked lists.

Optimized approach using in-place manipulation of a linked list

To reverse the entire linked list without occupying extra memory, we can utilize the in-place manipulation pattern. This pattern allows us to modify the directions of the nodes in the linked list directly by keeping track of the current, next, and previous nodes without the need for any additional data structures.