leetcode_solutions/189. Rotate Array.py at main · Rupeshhsharma/leetcode_solutions · GitHub

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             -----------------------------------Rotate Array------------------------------------------------

Given an integer array nums, 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]

#################################### solution (optimal)-----TC-O(N)####################################################3
class Solution:
    def rotate(self, nums: List[int], k: int) -> None:

        n = len(nums)
        k = k % n

        def reverse(start, end):
            while start < end:
                nums[start], nums[end] = nums[end], nums[start]
                start += 1
                end -= 1

        reverse(0, n-1)
        reverse(0, k-1)
        reverse(k, n-1)