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

    if(nums == null || nums.length < 2){
        return;
    }
    
    k = k % nums.length;
    reverse(nums, 0, nums.length - k - 1);
    reverse(nums, nums.length - k, nums.length - 1);
    reverse(nums, 0, nums.length - 1);
    
}

private void reverse(int[] nums, int i, int j){
    int tmp = 0;       
    while(i < j){
        tmp = nums[i];
        nums[i] = nums[j];
        nums[j] = tmp;
        i++;
        j--;
    }
}
}