Rotate a list right by 1
Input
rotate([1, 2, 3, 4], 1)
Output
[4, 1, 2, 3]
Right rotation by 1 moves the last element to the front.
Full lesson preview
Rotate a sequence using deque
Use collections.deque.rotate to rotate sequences efficiently and preserve type.
Python practice18 minModules & Standard LibraryIntermediateLast updated March 23, 2026
Problem statement
Write a function rotate(seq, k) that returns the sequence rotated to the right by k steps. If k is negative, rotate to the left. Use collections.deque and its rotate method for efficiency. The function should preserve the input type for lists and strings. For other sequence types you may return a list representing the rotated elements.
Task
Implement rotate(seq, k) that rotates a sequence by k positions using collections.deque. For lists return a list; for strings return a string.
Examples
Input format
A sequence (list or string) and an integer k: rotate(seq, k)
Output format
A rotated sequence of the same type (list -> list, string -> string).
Constraints
Use collections.deque.rotate for O(n) rotation with minimal overhead. Handle empty sequences and k values larger than the length by relying on deque behavior.
Samples
Sample 1
Input
rotate('abcd', 2)
Output
cdab
Right rotate string by 2: 'ab' moves to the end, resulting in 'cdab'.