189. Rotate Array LeetCode Java Solution

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 

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;
    k = k % n;
    Reverse(nums, n-k, n-1);
    Reverse(nums, 0, n-k-1);
    Reverse(nums, 0, n-1);
}

public static void Reverse(int[] nums, int i, int j) {
    while (i < j) {
        int temp = nums[i];
        nums[i] = nums[j];
        nums[j] = temp;

        i++;
        j--;
    }
		
    }
}