using System;

using System.Linq;

​

namespace ConsoleApp1

{

    public class Program

    {

        private const int UniqueChars = 4;

​

        private const int MaxSequenceNumber = 3;

​

        private static void Main(string[] args)

        {

            var pwds = new[] { "986522", "321795", "010118", "401239", "987332", "982123" };

​

            foreach (var pwd in pwds)

            {

                Console.WriteLine($"{pwd} = {IsValid(pwd)}");

            }

        }

​

        private static bool IsValid(string password)

        {

            if (password.Select(x => Convert.ToInt32(x)).Distinct().Count() < UniqueChars)

                return false;

​

            var currentSequence = 0;

​

            for (int i = 0; i < password.Length - 1; i++)

            {

                if (Convert.ToInt32(password[i].ToString()) + 1 == Convert.ToInt32(password[i + 1].ToString()) || Convert.ToInt32(password[i].ToString()) - 1 == Convert.ToInt32(password[i + 1].ToString()))

                {

                    currentSequence++;

​

                    if (currentSequence == MaxSequenceNumber - 1)

                        return false;

                }

                else

                    currentSequence = 0;

            }

​

            return true;

        }

    }

}