leetcode/apps/docs/content/(01-linear-structures)/two-pointers/189-rotate-array.mdx

---
title: '189. Rotate Array'
description: Given an integer array nums, rotate the array to the right by k steps, where k is non-negative
icon: dot
topics:
  - { name: "Array", slug: "array" }
  - { name: "Math", slug: "math" }
  - { name: "Two Pointers", slug: "two-pointers" }
issue: "https://github.com/prdlk/leetcode/issues/47"
sidebar:
  label: 'Rotate Array'
  badge: 'Medium'
---

### 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 <= 10^5`
- `-2^31 <= nums[i] <= 2^31 - 1`
- `0 <= k <= 10^5`
- 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

```py
class Solution:
    def rotate(self, nums: list[int], k: int) -> None:
        N = len(nums) - 1
        cut = k % len(nums)

        def reverse(l, r):
            while l <= r:
                nums[l], nums[r] = nums[r], nums[l]
                l += 1
                r -= 1

        reverse(0, N)
        reverse(0, cut - 1)
        reverse(cut, N)
```