## DEV Community

Abhishek Chaudhary

Posted on

# 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`

• 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?

SOLUTION:

``````class Solution:
def reverse(self, nums, a, b):
n = b - a
for i in range(n // 2):
nums[a + i], nums[a + n - i - 1] = nums[a + n - i - 1], nums[a + i]
return nums

def rotate(self, nums: List[int], k: int) -> None:
n = len(nums)
k = n - k % n
self.reverse(nums, 0, k)
self.reverse(nums, k, n)
self.reverse(nums, 0, n)
return nums
``````