uf_checker.cs

    public class UChecker:IDisposable
    {
        public int[,] CardSet;
        public int[,] PhomMark;
        private int _countNotPickedCard;

        private int _countCardNotInPhom;
        public int CountCardNotInPhom { get { return _countCardNotInPhom;} set{ _countCardNotInPhom = value;}}

        private int _countEatenCardInHand;
        public int CountEatenCardInHand { get { return _countEatenCardInHand; } set { _countEatenCardInHand = value; }}

        private int _countPhom;
        private bool _foundU;
        private int[,] _countPhomNgang;
        private int[,] _countPhomDoc;

        public List<List<int>> Phoms { get; private set; }

        public UChecker()
        {
            Phoms =
                new List<List<int>>();
        }

        private const short CardEaten = 2;

        private readonly short[][,] _loangDoc = {
                new short[,] {{0, 1, 2}, {0, 0, 0}},
                new short[,] {{0, 1, 3}, {0, 0, 0}},
                new short[,] {{0, 2, 3}, {0, 0, 0}},
                new short[,] {{0, 1, 2, 3}, {0, 0, 0, 0}}
            };

        public short[][,] LoangDoc
        {
            get { return _loangDoc; }
        }

        private readonly short[][,] _loangNgang =
            {
                new short[,] {{0, 0, 0}, {0, 1, 2}},
                new short[,] {{0, 0, 0, 0}, {0, 1, 2, 3}},
                new short[,] {{0, 0, 0, 0, 0}, {0, 1, 2, 3, 4}}
            };

        public short[][,] LoangNgang
        {
            get { return _loangNgang; }
        }

        public bool Check(int[,] cardSet)
        {
            CardSet = cardSet;
            Init();
            InnerCheck(0, 0);
            return _foundU;
        }

        public void Init()
        {
            PhomMark = new int[4, 13];
            _countPhomNgang = new int[4, 13];
            _countPhomDoc = new int[4, 13];
            _countNotPickedCard = 0;
            _countCardNotInPhom = 0;
            _countPhom = 0;
            _countEatenCardInHand = 0;
            _foundU = false;
            
            for (int i = 3; i >= 0; i--)
            {
                for (int j = 12; j >= 0; j--)
                {
                    int countNgang = 0;
                    int countDoc = 0;
                    int rightColumn = j + 1;
                    int belowRow = i + 1;
                    if (rightColumn < 13)
                    {
                        countNgang = _countPhomNgang[i, rightColumn];
                    }
                    if (belowRow < 4)
                    {
                        countDoc = _countPhomDoc[belowRow, j];
                    }
                    if (CardSet[i, j] != 0)
                    {
                        _countPhomNgang[i, j] = countNgang + 1;
                        _countPhomDoc[i, j] = countDoc + 1;
                    }
                    else
                    {
                        _countPhomNgang[i, j] = 0;
                        _countPhomDoc[i, j] = countDoc;
                    }
                    _countCardNotInPhom += CardSet[i, j] > 0 ? 1 : 0;
                    _countEatenCardInHand += CardSet[i, j] == CardEaten ? 1 : 0;
                }
            }
        }

        private void InnerCheck(int row, int column)
        {
            if (_foundU) return;

            bool foundNextCard = false;
            while (row < 4)
            {
                while (column < 13 && (CardSet[row, column] == 0 || PhomMark[row, column] != 0))
                {
                    column++;
                }

                if (column < 13)
                {
                    foundNextCard = true;
                    break;
                }

                column = 0;
                row++;
            }

            if (!foundNextCard) return;

            if (_countPhomDoc[row, column] >= 3)
            {
                for (int i = LoangDoc.Length - 1; i >= 0; i--)
                {
                    if (IsValidPhom(row, column, LoangDoc[i]))
                    {
                        _countPhom++;
                        _countCardNotInPhom -= LoangDoc[i].GetLength(1);
                        MarkPhom(row, column, LoangDoc[i], _countPhom);
                        if (ListPhomUValid())
                        {
                            _foundU = true;
                            PrintPhom();
                            return;
                        }
                        InnerCheck(row, column + 1);
                        if (_foundU) return;
                        UnmarkPhom(row, column, LoangDoc[i]);
                        _countCardNotInPhom += LoangDoc[i].GetLength(1);
                        _countPhom--;
                    }
                }
            }


            if (_countPhomNgang[row, column] >= 3)
            {
                for (int i = LoangNgang.Length - 1; i >= 0; i--)
                {
                    bool isValidPhom = IsValidPhom(row, column, LoangNgang[i]);
                    if (isValidPhom)
                    {
                        _countPhom++;
                        _countCardNotInPhom -= LoangNgang[i].GetLength(1);
                        MarkPhom(row, column, LoangNgang[i], _countPhom);
                        if (ListPhomUValid())
                        {
                            _foundU = true;
                            PrintPhom();
                            return;
                        }
                        InnerCheck(row, column + LoangNgang[i].GetLength(1));
                        if (_foundU) return;
                        UnmarkPhom(row, column, LoangNgang[i]);
                        _countCardNotInPhom += LoangNgang[i].GetLength(1);
                        _countPhom--;
                    }
                }
            }

            if (_countNotPickedCard == 0)
            {
                _countNotPickedCard++; // skip one card, u 9 cay
                InnerCheck(row, column + 1);
                if (_foundU) return;
                _countNotPickedCard--;
            }
        }

        public bool ListPhomUValid()
        {
            if (_countCardNotInPhom > 1) return false;

            var countEatenCardInPhom = 0;
            for (var i = 0; i < 4; i++)
            {
                for (var j = 0; j < 13; j++)
                {
                    if (PhomMark[i, j] != 0 && CardSet[i, j] == CardEaten)
                    {
                        countEatenCardInPhom++;
                    }
                }
            }

            if (countEatenCardInPhom != _countEatenCardInHand) return false;
            return true;
        }

        private void UnmarkPhom(int row, int column, short[,] loang)
        {
            MarkPhom(row, column, loang, 0);
        }

        private void MarkPhom(int row, int column, short[,] loang, int phomNumber)
        {
            for (int i = 0; i < loang.GetLength(1); i++)
            {
                int nextRow = row + loang[0, i];
                int nextColumn = column + loang[1, i];
                PhomMark[nextRow, nextColumn] = phomNumber;
            }
        }

        public bool IsValidPhom(int row, int column, short[,] loang)
        {
            var countEatenCard = 0;
            for (var i = 0; i < loang.GetLength(1); i++)
            {
                int nextRow = row + loang[0, i];
                int nextColumn = column + loang[1, i];
                if (nextRow >= 4 || nextColumn >= 13) return false;
                if (CardSet[nextRow, nextColumn] == 0 || PhomMark[nextRow, nextColumn] != 0)
                {
                    return false;
                }

                if (CardSet[nextRow, nextColumn] == CardEaten)
                {
                    countEatenCard++;
                }
            }

            if (countEatenCard > 1)
            {
                return false; // 1 phỏm không thể có 2 cây ăn
            }
            return true;
        }

        public static bool CheckUKhan(int[,] cardSet)
        {
            for (var i = 0; i < 13; i++)
            {
                var count = cardSet[0, i] + cardSet[1, i] + cardSet[2, i] + cardSet[3, i];
                if (count >= 2)
                {
                    // found ca. ngang
                    return false;
                }
            }

            for (var i = 0; i < 4; i++)
            {
                var j = 0;
                while (j < 12)
                {
                    if (cardSet[i, j] == 1)
                    {
                        if (cardSet[i, j + 1] == 1)
                        {
                            // found ca. do.c kieu 5 tep, 6 tep
                            return false;
                        }
                        if (j < 11 && cardSet[i, j + 2] == 1)
                        {
                            // found ca. do.c kieu 5 tep, 7 tep
                            return false;
                        }
                    }

                    j++;
                }
            }

            return true;

        }

        public static bool CheckUKhan(IList<int> cards)
        {
            var cardSet = new int[4, 13];

            for (var i = 0; i < 4; i++)
            {
                for (var j = 0; j < 13; j++)
                {
                    cardSet[i, j] = 0;
                }
            }

            for (var i = 0; i < cards.Count; i++)
            {
                var card = new Card(cards[i]);
                cardSet[(int)card.Class, card.Value] = 1;
            }

            return CheckUKhan(cardSet);
        }

        public bool Check(IList<int> cards, IList<int> eatenCards)
        {
            var cardSet = new int[4, 13];

            for (var i = 0; i < 4; i++)
            {
                for (var j = 0; j < 13; j++)
                {
                    cardSet[i, j] = 0;
                }
            }

            for (var i = 0; i < cards.Count; i++)
            {
                var card = new Card(cards[i]);
                if (eatenCards.Contains(cards[i]))
                {
                    cardSet[(int)card.Class, card.Value] = CardEaten;     
                }
                else
                {
                    cardSet[(int)card.Class, card.Value] = 1;
                }
            }

            return Check(cardSet);

        }

        [Obsolete("Now to check U, must pass in eaten card list. Call Check(IList<int>, IList<int>) instead.")]
        public bool Check(IList<int> cards)
        {
            return Check(cards, new List<int>());
        }

        private void ClearPhomMarks()
        {
            for (var i = 0; i < 4; i++)
            {
                for (var j = 0; j < 13; j++)
                {
                    PhomMark[i, j] = 0;
                }
            }
        }

        private void PrintPhom()
        {
            var phomA = new List<int>();
            var phomB = new List<int>();
            var phomC = new List<int>();

            for (var i = 0; i < 4; i++)
            {
                for (var j = 0; j < 13; j++)
                {
                    var rawCard = i * 13 + j;

                    switch (PhomMark[i, j])
                    {
                        case 1:
                            phomA.Add(rawCard);
                            break;
                        case 2:
                            phomB.Add(rawCard);
                            break;
                        case 3:
                            phomC.Add(rawCard);
                            break;
                    }
                }
            }

            if (phomA.Count > 0)
            {
                Phoms.Add(phomA);
            }
            if (phomB.Count > 0)
            {
                Phoms.Add(phomB);
            }
            if (phomC.Count > 0)
            {
                Phoms.Add(phomC);
            }

            ClearPhomMarks();
        }

        public void Dispose()
        {
        }
    }