189.RotateArray.java

class Solution {
//time complexity:O(n), space: O(1)
    public void rotate(int[] nums, int k) {
        int n= nums.length;
        k = k % n;
        reverse(nums, 0, n-1);
        reverse(nums, 0, k-1);
        reverse(nums, k, n-1);
        
    }
    public void reverse(int[] nums, int start, int end){
        while(start < end){
            int temp = nums[start];
            nums[start] = nums[end];
            nums[end] = temp;
            start++;
            end--;
        }
    }
}