Reverse array in groups

Original Problem: Reverse an Array in Groups of Given Size Using Chunking Technique (Reversal) We want to reverse an array in groups of size k . Think of the array as being split into consecutive chunks (windows) of length k , and we reverse each chunk one by one. Key Idea (Chunk-by-Chunk) Start from index 0 . Take the next k elements as a chunk: array[i : i+k] . Reverse only that chunk. Jump to the next chunk by moving i forward by k . Algorithm Steps Loop through the array in steps of k : i = 0, k, 2k, 3k, ... Reverse the current chunk: Replace array[i : i+k] with its reversed version. Handle the edge case (last chunk smaller than k ): If fewer than k elements remain, array[i : i+k] simply returns the remaining elements. Reversing it still works, so no extra checks are needed. Implementation def reverse_in_groups ( arr , k ): n = len ( arr ) for i in range ( 0 , n , k ): # Reverse the sub-array from i to i+k arr [ i : i + k ] = reversed ( arr [ i : i + k ]) return arr Time Complexity