rotateArray

rotateArray.py

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

        # Reversing the whole array 12345 -> 54321
        l, r = 0, len(nums) - 1
        while l < r:
            nums[l], nums[r] = nums[r], nums[l]
            l, r = l + 1, r - 1

        # reverse first part where end is k
        l, r = 0, k - 1
        while l < r:
            nums[l], nums[r] = nums[r], nums[l]
            l, r = l + 1, r - 1

        # reverse the remaining part
        l, r = k, len(nums) - 1
        while l < r:
            nums[l], nums[r] = nums[r], nums[l]
            l, r = l + 1, r - 1

Toolkit: Reverse elements of array