Linked List K-Position Reversal | Dataford Interview Questions

An Xfinity service diagnostic tool stores ordered event codes in a Python list. To support a processing mode used by Comcast test automation, reverse the order of events within every consecutive group of k elements.

Modify the list in place and return the same list. If the final group contains fewer than k elements, leave that final group unchanged.

Formal Specification

Implement reverse_in_groups(items, k).

Input: items, a list of integers, and k, a positive integer.
Output: The same list object, with each complete group of k consecutive elements reversed.
The relative order between separate groups must not change.
Use only constant auxiliary space, excluding the input list.

Constraints

1 <= len(items) <= 10^5
1 <= k <= len(items)
-10^9 <= items[i] <= 10^9
The final group is unchanged when its size is less than k
The list must be modified in place

Function Signature

def reverse_in_groups(items, k):

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