Solution: Reverse Nodes in k-Group

Explore how to reverse nodes in a linked list in groups of k without extra memory allocation. This lesson teaches you to identify k-node groups, reverse them in place, and reattach to the list, improving time and space efficiency for coding interview problems.

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Statement
Solution
- Naive approach
- Optimized approach using in-place manipulation of a linked list

Statement

The task is to reverse the nodes in groups of $k$ in a given linked list, where $k$ is a positive integer, and at most the length of the linked list. If any remaining nodes are not part of a group of $k$ , they should remain in their original order.

It is not allowed to change the values of the nodes in the linked list. Only the order of the nodes can be modified.

Note: Use only $O(1)$ extra memory space.

Constraints:

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

$1 \leq$ k $\leq$ n $\leq 500$
$0 \leq$ Node.value $\leq 1000$

Solution

So far, you’ve probably brainstormed some approaches and have an idea of how to solve this problem. Let’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

A naive approach would be to use another data ...