--- 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" companies: - { name: "Bloomberg", period: "Thirty Days", frequency: 69.8 } - { name: "Microsoft", period: "Thirty Days", frequency: 67.9 } - { name: "Amazon", period: "Thirty Days", frequency: 48.9 } - { name: "Google", period: "Thirty Days", frequency: 46.6 } - { name: "Infosys", period: "Three Months", frequency: 66 } - { name: "tcs", period: "Three Months", frequency: 57.2 } - { name: "Meta", period: "Three Months", frequency: 54.8 } - { name: "Box", period: "Six Months", frequency: 100 } - { name: "TikTok", period: "Six Months", frequency: 55.2 } - { name: "Apple", period: "Six Months", frequency: 48.1 } 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) ```