The challenge
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 <= 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:]