# Leetcode claiming incorrect answer when it's inarguably correct

I’m trying to complete the 189. Rotate Array problem on Leetcode.
This is the code I’ve written:

``````class Solution(object):
def rotate(self, nums, k):
end = len(nums) - 1
carry = []
new = [n for n in nums]
for i in range(end-k+1, end+1):
carry.append(nums[i])
for i in range(1, k+1):
new.pop()
for n in new:
carry.append(n)
print(carry)
return carry
``````

(The obsolete variables were to try and erase any possibility of something wacky happening with Leetcode’s testing system.)

I can run this code anywhere (I’ve tried VS Code and an online interpreter) and the result is always correct (for the first case, [5, 6, 7, 1, 2, 3, 4]).
However, when I try in Leetcode:

The stdout shows the correct answer literally the line before the return, and yet the array somehow magically changes through no tampering.

(Problem description:

``````Given an array, rotate the array to the right by k steps, where k is non-negative.

Example 1:

Input: nums = [1,2,3,4,5,6,7], k = 3
Output: [5,6,7,1,2,3,4]
Explanation:
rotate 1 steps to the right: [7,1,2,3,4,5,6]
rotate 2 steps to the right: [6,7,1,2,3,4,5]
rotate 3 steps to the right: [5,6,7,1,2,3,4]
Example 2:

Input: nums = [-1,-100,3,99], k = 2
Output: [3,99,-1,-100]
Explanation:
rotate 1 steps to the right: [99,-1,-100,3]
rotate 2 steps to the right: [3,99,-1,-100]

Constraints:

1 <= nums.length <= 105
-231 <= nums[i] <= 231 - 1
0 <= k <= 105

Try to come up with as many solutions as you can. There are at least three different ways to solve this problem.
Could you do it in-place with O(1) extra space?
``````

)

### >Solution :

The Python template for this problem says:

``````class Solution:
def rotate(self, nums: List[int], k: int) -> None:
"""
Do not return anything, modify nums in-place instead.
"""
``````

As the docstring mentioned, you’ll need to modify `nums` in-place. There is no need to print or return anything.

A simple fix to your existing code would be to use an assignment `nums[:] = carry` at the end.