Rotate Array problem leetcode

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]

 

Constraints:

1 <= nums.length <= 105

-231 <= nums[i] <= 231 - 1

0 <= k <= 105

 

Follow up:

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 {

    public void rotate(int[] nums, int k) {

        int n = nums.length;

       

        // Create a temporary array to store rotated elements

        int[] arr = new int[n];

        // Place each element at its new position in the temporary array

        for (int i = 0; i < n; i++) {

            arr[(i + k) % n] = nums[i]; // Calculate new index for each element //use modulo

// for those element whose shift after n-1 position .

        }

        // Copy the rotated elements back to the original array

        for (int i = 0; i < n; i++) {

            nums[i] = arr[i];

        }

    }

}

2nd Approac -

class Solution {

    public void rotate(int[] nums, int k) {

        int n = nums.length;

        k = k % n; // Handle large k values

        

        // Step 1: Reverse the whole array

        reverse(nums, 0, n - 1);

        

        // Step 2: Reverse the first k elements

        reverse(nums, 0, k - 1);

        

        // Step 3: Reverse the remaining n-k elements

        reverse(nums, k, n - 1);

    }

    

    private void reverse(int[] nums, int start, int end) {

        while (start < end) {

            int temp = nums[start];

            nums[start] = nums[end];

            nums[end] = temp;

            start++;

            end--;

        }

    }

}