using System;

public class Program

{

    public static void Main()

    {

        // TC 1

        //int[] digits = {1,2,3};

        //string expected = "[1,2,4]";

        // TC 2

        //int[] digits = {9,8,7,6,5,4,3,2,1,0};

        //string expected = "[9,8,7,6,5,4,3,2,1,1]";

        // TC 3

        int[] digits = {2,1,4,7,4,8,3,6,4,6};

        string expected = "[2,1,4,7,4,8,3,6,4,7]";

        //int[] results = PlusOne(digits);

        int[] results = WhileLoop(digits);

        string result = "[";

        for (int i = 0; i < results.Length; i++)

            result += results[i] + ",";

        result = result.TrimEnd(',');

        result += "]";

        Console.WriteLine("Output: {0}", result);

        Console.WriteLine("Expected: {0}", expected);

    }

    public static int[] PlusOne(int[] digits) {

        if (digits[digits.Length - 1] != 9) 

        {

            digits[digits.Length - 1] += 1;

            return digits;

        }

        if (digits[0] != 9)

        {

            for (int i = digits.Length - 1; i > 0; i--)

            {

                if ((digits[i] == 9 && i == digits.Length - 1) || digits[i] == 10)

                {

                    digits[i] = 0;

                    digits[i - 1] += 1;

                }

                else

                    return digits;

            }

        } else {

            int[] nums = new int[digits.Length + 1];

            for (int i = digits.Length - 1; i >= 0; i--)

            {

                if ((digits[i] == 9 && i == digits.Length - 1) || digits[i] == 10)

                {

                    nums[i + 1] = 0;

                    digits[i] = 0;

                    if (i - 1 >= 0) {

                        nums[i] = digits[i - 1] + 1;

                        digits[i - 1] += 1;

                    } else {

                        nums[i] = 1;

                        return nums;

                    }

                }

                else

                    return digits;

            }

        }

        return digits;

    }

    public static int[] WhileLoop(int[] digits) {

        int i = digits.Length - 1;

        while (i >= 0)

        {

            if (digits[i] < 9) {

                digits[i] += 1;

                return digits;

            }

            else 

                digits[i--] = 0;

        }

        int[] nums = new int[digits.Length + 1];

        nums[0] = 1;

        return nums;

    }

}