189 Rotate Array

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

Follow up:

• 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?

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class Solution:
    def rotate(self, nums: List[int], k: int) -> None:
        """
        Do not return anything, modify nums in-place instead.
        """
        n = len(nums)
        k = k % n
        self.reverse(nums, 0, n-k-1)
        self.reverse(nums, n-k, n-1)
        self.reverse(nums, 0, n-1)

    def reverse(self, nums: List[int], i:int, j:int) -> None:
        while i < j:
            nums[i], nums[j] = nums[j], nums[i]
            i += 1
            j -= 1