Rotate example
Input
rotate_right([1, 2, 3, 4, 5], 2)
Output
[4, 5, 1, 2, 3]
Array rotated right by 2 positions.
Full lesson preview
Rotate an array right by k
Rotate the elements of an array to the right by k steps, in-place.
Python practice8 minArrays – Fundamentals & PatternsBeginnerLast updated March 25, 2026
Problem statement
Given a list arr and a non-negative integer k, rotate arr to the right by k steps in-place and return the modified list. For example, rotating [1,2,3,4,5] by k=2 yields [4,5,1,2,3]. Your solution should handle k >= len(arr) by using k modulo len(arr).
Task
Implement an in-place right rotation of a list by k positions using O(1) extra space.
Examples
Input format
Two arguments: a list of integers and a non-negative integer k.
Output format
The same list rotated right by k positions and returned (list).
Constraints
- 0 <= len(arr) <= 10^5
- 0 <= k <= 10^9
- Must rotate using O(1) extra space and O(n) time
Samples
Sample 1
Input
rotate_right([1, 2, 3], 3)
Output
[1, 2, 3]
k equal to array length results in the same array.