Reverse Array K Rotations | Dataford Interview Questions

Your question is Reverse Array K Rotations. Start with the requirements on the right.

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Problem

ABC Education's learner progress service stores ordered lesson identifiers in an array. Given an integer array nums and a non-negative integer k, rotate the array to the right by k positions and return the modified array.

Provide two solutions in this order:

Brute force: move the last element to the front one position at a time.
Optimal: use three in-place reversals. You must implement the reversal helper yourself and may not call a library reverse function or create a second array proportional to nums.

Formal Specification

Input: nums, a mutable array of integers, and k, a non-negative integer.
Output: The same array object after a right rotation by k positions.
Rotation should treat values in the original array as circular. Rotating by the array length, or any multiple of it, leaves the array unchanged.

Constraints

0 <= nums.length <= 10^5
0 <= k <= 10^9
-10^9 <= nums[i] <= 10^9
Modify nums in place.
Use O(1) auxiliary space.
Do not call a library reverse or rotation function.

Function Signature

def rotate(nums, k):