189. Rotate Array

1. Description

Given an integer array nums, rotate the array to the right by k steps, where k is non-negative.

2. Example

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]

3. Constraints

• 1 <= nums.length <= $10^5$
• -$2^{31}$ <= nums[i] <= $2^{31}$ - 1
• 0 <= k <= $10^5$

4. Solutions

Reverse

n = nums.size()
Time complexity: O(n)
Space complexity: O(1)

class Solution {
public:
    void rotate(vector<int> &nums, int k) {
        const int n = nums.size();
        if ((k % n) != 0) {
            k %= n;
            reverse(nums.begin(), nums.end());

            reverse(nums.begin(), nums.begin() + k);
            reverse(nums.begin() + k, nums.end());
        }
    }
};