public void BubbleSort(int[] arr)
        {
            for (int i = 1; i < arr.Length; i++)
                for (int j = 0; j < arr.Length - i; j++)
                {
                    if (arr[j] > arr[j + 1])
                    {
                        int tmp = arr[j];
                        arr[j] = arr[j + 1];
                        arr[j + 1] = tmp;
                    }
                }
        }

        public int HalfSearch(int key, int[] arr)
        {
            int left = 0;
            int right = arr.Length - 1;

            while (left <= right)
            {
                int middle = (left + right) / 2;

                if (key == arr[middle])
                    return middle;
                else if (key > arr[middle])
                {
                    left = middle + 1;
                }
                else
                {
                    right = middle - 1;
                }
            }
            return -1;
        }