Final RiTangle Working Q20

/*
IN C#
fraudseter guessing 6 digit password
in some order the password features the digits 123 twice each
"additionally, he knows that no consecutive pair of digits are the same"
what to 3sf is his chance of a successful random guess
*/



using System;
using System.Collections.Generic;
using System.Linq;

internal class Program
{
    private static void Main(string[] args)
    {
        // Create a list to store generated numbers
        List<int> master_list = new List<int>();
        Console.WriteLine("Working");

        // Generate 620 unique 6-digit numbers and add them to the master list
        for (int i = 0; i < 620; i++)
        {
            // Generate a new 6-digit number
            int new_number = CreateNewNumber();

            // Ensure the new number is not a duplicate
            if (!master_list.Contains(new_number))
            {
                master_list.Add(new_number);
            }
        }

        // Display information about the master list
        Console.WriteLine($"Created the master list\n{master_list.Count} items in it");
        Console.WriteLine($"{string.Join(", ", master_list)}");

        // Filter the master list based on conditions and create a final list
        List<int> final_list = MakeFinalList(master_list);

        // Display information about the final list
        Console.WriteLine($"Created the final list\n{final_list.Count} items in it");
        Console.WriteLine($"{string.Join(", ", final_list)}");
    }

    // Function to generate a random 6-digit number with digits 1, 2, and 3 appearing twice each
    static int CreateNewNumber()
    {
        // String to store the generated number
        string big_number = "";

        // List of available digits (1, 1, 2, 2, 3, 3)
        List<int> digits_possible = new List<int> {1, 1, 2, 2, 3, 3};

        // Loop until all digits are used
        while (digits_possible.Count() != 0)
        {
            // Create a random number generator
            Random random = new Random();

            // Randomly select a digit
            int random_index = random.Next(0, digits_possible.Count);
            int random_digit = digits_possible[random_index];

            // Remove the selected digit from the list
            digits_possible.RemoveAt(random_index);

            // Append the digit to the number
            big_number += random_digit;
        }

        // Convert the string to an integer and return the generated number
        return int.Parse(big_number);
    }

    // Function to filter a list based on conditions
    static List<int> MakeFinalList(List<int> old_list)
    {
        // List to store the final filtered numbers
        List<int> new_list = new List<int>();

        // Iterate over each number in the old list
        foreach (int number in old_list)
        {
            // Convert the number to a string for digit-level analysis
            string number_as_string = number.ToString();

            // Ensure that the digits 1, 2, and 3 appear exactly twice each
            if (number_as_string.Count(c => c == '1') == 2 &&
                number_as_string.Count(c => c == '2') == 2 &&
                number_as_string.Count(c => c == '3') == 2)
            {
                // Check for no consecutive pair of digits being the same
                bool add_to_new_list = true;
                for (int i = 0; i < 5; i++)
                {
                    if (number_as_string[i] == number_as_string[i + 1])
                    {
                        // If consecutive digits are the same, set flag to false and break the loop
                        add_to_new_list = false;
                        break;
                    }
                }

                // If all conditions are met, add the number to the new list
                if (add_to_new_list)
                {
                    new_list.Add(number);
                }
            }
        }

        // Return the final filtered list
        return new_list;
    }
}