Rotate Array with O(n) complexity and O(1) space

RotateArray.java

public class RotateArray {
  
    public void rotate(int[] nums, int k) {
        
        if(k > nums.length) k = k % nums.length;
        
        reverse(nums, 0, nums.length);
        reverse(nums, 0, k);
        reverse(nums, k, nums.length);
    }
    
    private void reverse(int[] ar, int from, int upTo){
        
        if(upTo <= from) return;
        
        int l = upTo - from;
        int mid = (from + l /2);
        
        for(int i = from, j = upTo - 1; i < mid && j >= mid ; i++, j--){
            
            int temp = ar[i];
            ar[i] = ar[j];
            ar[j] = temp;
        }
    }
}