01.03.Bulls and Cows мое решение Linq и List

using System;
using System.Collections.Generic;
using System.Linq;
class BullsAndCows
{
    static void Main()
    {
        int secretNumber = int.Parse(Console.ReadLine());

        int bulls = int.Parse(Console.ReadLine());
        int cows = int.Parse(Console.ReadLine());
        bool isAnyFound = false;
        for (int guessNumber = 1111; guessNumber < 10000; guessNumber++)
        {
            if (Convert.ToString(guessNumber).IndexOf('0') > -1)
            {
                continue;
            }
            int bullsFound = FindBulls(guessNumber, secretNumber);
            int cowsFound = FindCows(guessNumber, secretNumber);
            if (bullsFound == bulls && cowsFound == cows)
            {
                isAnyFound = true;
                Console.Write(guessNumber + " ");
            }
        }
        if (!isAnyFound)
        {
            Console.WriteLine("No");
        }
    }

    static int FindCows(int guessNumber, int secretNumber)
    {
        int cowsCount = 0;
        List<char> guessNum = Convert.ToString(guessNumber).ToList();//със linq го конвертирам в лист
        List<char> secretNum = Convert.ToString(secretNumber).ToList();
        for (int i = 0; i < 4; i++)
        {
            if (guessNum[i] == secretNum[i])
            {
                guessNum[i] = '*';
                secretNum[i] = '*';
            }
        }

        for (int i = 0; i < 4; i++)
        {
            if (guessNum[i] != '*' && secretNum.Contains(guessNum[i]))//ако е различно от '*' и го има имаме крава
            {
                cowsCount++;
                secretNum.Remove(guessNum[i]);//по този начин премахвам който си искам елeмент, а не на позиция i
            }
        }
        return cowsCount;
    }

    static int FindBulls(int guessNumber, int secretNumber)
    {
        int bullsCount = 0;
        int guessA = (guessNumber / 1) % 10;
        int guessB = (guessNumber / 10) % 10;
        int guessC = (guessNumber / 100) % 10;
        int guessD = (guessNumber / 1000) % 10;

        if (guessA == (secretNumber / 1) % 10)
        {
            bullsCount++;
        }
        if (guessB == (secretNumber / 10) % 10)
        {
            bullsCount++;
        }
        if (guessC == (secretNumber / 100) % 10)
        {
            bullsCount++;
        }
        if (guessD == (secretNumber / 1000) % 10)
        {
            bullsCount++;
        }
        return bullsCount;
    }
}