https://practice.geeksforgeeks.org/problems/reverse-array-in-groups0255/1
Given an array arr[] of positive integers of size N. Reverse every sub-array group of size K.
Example 1:
Input: N = 5, K = 3 arr[] = {1,2,3,4,5} Output: 3 2 1 5 4 Explanation: First group consists of elements 1, 2, 3. Second group consists of 4,5.
Example 2:
Input: N = 4, K = 3 arr[] = {5,6,8,9} Output: 8 6 5 9
Your Task: You don't need to read input or print anything. The task is to complete the function reverseInGroups() which takes the array, N and K as input parameters and modifies the array in-place.
Expected Time Complexity: O(N) Expected Auxiliary Space: O(N)
Constraints: 1 ≤ N, K ≤ 10^7 1 ≤ A[i] ≤ 10^18