[Array] 배열 회전하기

1차원 배열 회전하기

---

/**
 * Rotate 1-dimensional Array
 * Time complexity:  O(n)
 * Space complexity: O(1)
 * */
public class Rotate {
    private static final Logger logger = Logger.getLogger(Rotate.class.getName());

    public static void main(String[] args) {
        int[] nums = {1, 2, 3, 4, 5, 6, 7, 8, 9};
        int len = nums.length;
        int k = 12 % len;

        /* rotate right */
        rotate(nums, 0, k-1, len-1);
        logger.info("rotated right: " + Arrays.toString(nums));

        /* rotate left */
        rotate(nums, 0, len-k-1, len-1);
        logger.info("rotated left: "  + Arrays.toString(nums));
    }

    private static void rotate(int[] nums, int left, int mid, int right) {
        reverse(nums, left, right);
        reverse(nums, left, mid);
        reverse(nums, mid+1, right);
    }

    private static void reverse(int[] nums, int left, int right) {
        while(right > left) {
            int tmp = nums[right];
            nums[right--] = nums[left];
            nums[left++] = tmp;
        }
    }
}

1차원 배열 회전 결과