01.05.Bulls and Cows - Ники решение с List

using System;
using System.Collections.Generic;
class BullsAndCows
{
    static void Main()
    {
        int secretNumber = int.Parse(Console.ReadLine());
        int bulls = int.Parse(Console.ReadLine());
        int cows = int.Parse(Console.ReadLine());
        int result = 0;
        for (int guessNumber = 1111; guessNumber <= 9999; guessNumber++)
        {
            int bullsCount = 0, cowsCount = 0;

            int guessCurrentA = guessNumber / 1000 % 10;
            int guessCurrentB = guessNumber / 100 % 10;
            int guessCurrentC = guessNumber / 10 % 10;
            int guessCurrentD = guessNumber / 1 % 10;

            if(guessCurrentA == 0 || guessCurrentB == 0
                || guessCurrentC == 0 || guessCurrentD == 0)
            {
                continue;
            }
            int secretCurrentA = secretNumber / 1000 % 10;
            int secretCurrentB = secretNumber / 100 % 10;
            int secretCurrentC = secretNumber / 10 % 10;
            int secretCurrentD = secretNumber / 1 % 10;

            if (guessCurrentA == secretCurrentA)
            {
                bullsCount++;
                guessCurrentA = -1;
                secretCurrentA = -1;
            }
            if (guessCurrentB == secretCurrentB)
            {
                bullsCount++;
                guessCurrentB = -1;
                secretCurrentB = -1;
            }
            if (guessCurrentC == secretCurrentC)
            {
                bullsCount++;
                guessCurrentC = -1;
                secretCurrentC = -1;
            }
            if (guessCurrentD == secretCurrentD)
            {
                bullsCount++;
                guessCurrentD = -1;
                secretCurrentD = -1;
            }
            List<int> check = new List<int>();
            if (guessCurrentA > 0)
            {
                check.Add(guessCurrentA);
            }
            if (guessCurrentB > 0)
            {
                check.Add(guessCurrentB);
            }
            if (guessCurrentC > 0)
            {
                check.Add(guessCurrentC);
            }
            if (guessCurrentD > 0)
            {
                check.Add(guessCurrentD);
            }

            if (check.Contains(secretCurrentA))
            {
                cowsCount++;
                check.Remove(secretCurrentA);
            }
            if (check.Contains(secretCurrentB))
            {
                cowsCount++;
                check.Remove(secretCurrentB);
            }
            if (check.Contains(secretCurrentC))
            {
                cowsCount++;
                check.Remove(secretCurrentC);
            }
            if (check.Contains(secretCurrentD))
            {
                cowsCount++;
                check.Remove(secretCurrentD);
            }
            if (cowsCount == cows && bullsCount == bulls)
            {
                result = 1;
                Console.Write(guessNumber);
                Console.Write(" ");
            }
        }
        if (result == 0)
        {
            Console.WriteLine("No");
        }
    }
}