var array = new int[] { 1, 8, 2, 0, 4, 3, 7, 6, 5 };

            int inv_count = 0;
            for (int i = 0; i < array.Length - 1; i++) {
                for (int j = i + 1; j < array.Length; j++)
                {
                    if (array[i] > array[j])
                        inv_count++;
                }   
            }
            return inv_count;
        }