The challenge

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

Example 1:

Example 2:

Constraints:

  • 1 <= nums.length <= 2 * 10^4
  • It’s guaranteed that nums[i] fits in a 32 bit-signed integer.
  • k >= 0

The solution in Python

Option 1 could be as follows:

# update an array/list in-place
def rotate(self, nums: List[int], k: int) -> None:
    # loop `k` amount of times
    for i in range(k):
        # set previous temp variable
        # .. to the last item
        prev = nums[-1]
        # loop through the array/list
        for j in range(len(nums)):
            # swap the elements
            nums[j], prev = prev, nums[j]

Another way to do this is to make use of Python’s Splicing methodology:

# update an array/list in-place
def rotate(self, nums: List[int], k: int) -> None:
    k %= len(nums)
    nums[k:], nums[:k] = nums[:-k], nums[-k:]