DouKaku?

using System;

namespace Poker
{
    class Program
    {
        static void Main(string[] args)
        {
            if (args.Length != 1)
                return;

            Poker poker = new Poker(args[0]);
            Console.WriteLine(poker.Judge());
        }
    }

    public class Poker
    {
        static string RANK = "A23456789TJQK";
        string cards;
        string ranks;

        public Poker(string card)
        {
            cards = card;
            ranks = SortRanks();
        }

        public string Judge()
        {
            bool isRoyalStraight = ranks == "ATJQK";
            bool isStraight = RANK.IndexOf(ranks) >= 0;
            bool isFlush = IsFlush();
            string sameRanks = GetSameRanks();

            if (isRoyalStraight && isFlush)
                return "Royal flush";
            else if (isStraight && isFlush)
                return "Straight flush";
            else if (isStraight)
                return "Straight";
            else if (isFlush)
                return "Flush";
            else if (sameRanks == "4")
                return "Four of a kind";
            else if (sameRanks == "23")
                return "Full house";
            else if (sameRanks == "3")
                return "Three of a kind";
            else if (sameRanks == "22")
                return "Two pair";
            else if(sameRanks == "2")
                return "One pair";
            else
                return "No pair";
        }

        private string GetSameRanks()
        {
            int[] rankArray = new int[13];
            string sameRanks = "";

            for (int i = 0; i < rankArray.Length; i++)
                rankArray[i] = 0;

            for (int i = 0; i < ranks.Length; i++) {
                switch (ranks[i]) {
                    case 'A':
                    rankArray[0]++;
                    break;
                    case 'T':
                    rankArray[9]++;
                    break;
                    case 'J':
                    rankArray[10]++;
                    break;
                    case 'Q':
                    rankArray[11]++;
                    break;
                    case 'K':
                    rankArray[12]++;
                    break;
                    default:
                    rankArray[ranks[i] - 48 - 1]++;
                    break;
                }
            }

            Array.Sort(rankArray);
            foreach (int n in rankArray) {
                if (n > 1)
                    sameRanks += n.ToString();
            }

            return sameRanks;
        }

        private bool IsFlush()
        {
            char suit = cards[0];
            for (int i = 2; i < cards.Length; i += 2) {
                if (cards[i] != suit)
                    return false;
            }

            return true;
        }

        private string SortRanks()
        {
            char[] rankBuff = new char[5];
            string sortedRank = "";

            for (int i = 0; i < rankBuff.Length; i++)
                rankBuff[i] = cards[i * 2 + 1];

            for (int i = 0; i < RANK.Length; i++) {
                char c = RANK[i];
                foreach (char c2 in rankBuff) {
                    if (c == c2)
                        sortedRank += c.ToString();
                }
            }

            return sortedRank;
        }
    }
}