Ex02, 13.09.2021

using System;

namespace ConsoleApp5
{
    class Program
    {
        static void Main(string[] args)
        {
            // a number from user
            int n;

            // 10 counters (0 to 9) for each digit
            int[] count = new int[10];

            // get a number from user
            Console.Write("Enter a positive integer number: ");
            n = int.Parse(Console.ReadLine());

            // loop for each digit in the number n
            while (n > 0)
            {
                int ahad = n % 10; // first digit only
                n /= 10; // remove first digit from the number

                // update counter for the first digit found
                count[ahad]++;
            }

            // print digits and counters
            for (int i = 0; i < 10; i++)
            {
                // if digit exist in the number
                if (count[i] > 0)
                {
                    Console.WriteLine("{0} x {1}", i, count[i]);
                }
            }

            // build max number with the same digits
            string max = "";
            // loop for each digit, start from 9 down to 0
            for (int i = 9; i >= 0; i--)
            {
                // loop to add digit to max
                for (int c = 0; c < count[i]; c++)
                {
                    max += i;
                }
            }
            Console.WriteLine("max number with the same digits is {0}", max);
        }
    }
}