using System;

using System.Linq;

​

namespace ConsoleApp1

{

    public class Program

    {

        private const int UniqueChars = 4;

​

        private const int MaxSequenceNumber = 4;

​

        private static void Main(string[] args)

        {

            var pwds = new[] { "765412", "295678", "934561", "401239", "982123", "986522", "321795", "010118", "987332", "082941" };

​

            Console.WriteLine($"\n\tunique {UniqueChars}");

            Console.WriteLine($"\tmax sequence size {MaxSequenceNumber}");

​

            foreach (var pwd in pwds)

            {

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

            }

        }

​

        private static bool IsValid(string password)

        {

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

                return false;

​

            if (password.StartsWith("0"))

                return false;

​

            var currentSequence = 0;

            var lastSign = 0;

​

            var converted = password.Select(x => Convert.ToInt32(x.ToString())).ToArray();

​

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

            {

                var current = converted[i];

                var next = converted[i + 1];

​

                if ((Math.Max(current, next) - Math.Min(current, next)) == 1)

                {

                    var currentSign = current - next;

​

                    if (lastSign != currentSign)

                    {

                        lastSign = currentSign;

                        currentSequence = 0;

                    }

​

                    currentSequence++;

​

                    if (currentSequence == MaxSequenceNumber - 1)

                        return false;

                }

                else

                {

                    currentSequence = 0;

                    lastSign = 0;

                }

            }

​

            return true;

        }

    }

}