Пример #1
0
        static int MultSymbolsFromPosToPos(int[] seq, int startPos, int endPos)
        {
            int mult = 1;

            for (var i = startPos; i <= endPos; i++)
            {
                mult = Symb.Mult(mult, seq[i]);
            }
            return(mult);
        }
Пример #2
0
        static IEnumerable <int> FindAllKPos(int[] seq)
        {
            int mult = 1;

            for (var i = seq.Length - 1; i >= 0; i--)
            {
                mult = Symb.Mult(seq[i], mult);
                if (mult == Symb.k)
                {
                    yield return(i);
                }
            }
        }
Пример #3
0
        static IEnumerable <int> FindAllIPos(int[] seq)
        {
            int mult = 1;

            for (var i = 0; i < seq.Length; i++)
            {
                mult = Symb.Mult(mult, seq[i]);
                if (mult == Symb.i)
                {
                    yield return(i);
                }
            }
        }
Пример #4
0
        static string Solve(Tuple <long, int[]> d)
        {
            long r = d.Item1;

            int[] seq = d.Item2;

            if (r == 1)
            {
                var possibleIPos = FindAllIPos(seq).ToList();
                var possibleKPos = FindAllKPos(seq).Reverse().ToList();

                if (!possibleIPos.Any() || !possibleKPos.Any())
                {
                    return("NO");
                }

                //possibleKPos.Reverse();
                //possibleKPos = possibleKPos.Where(kp => kp > (possibleIPos[0] + 1)).ToList();

                Dictionary <int, int> nextKPosMult = new Dictionary <int, int>();
                for (var i = 1; i < possibleKPos.Count; i++)
                {
                    var cur  = possibleKPos[i];
                    var prev = possibleKPos[i - 1];
                    nextKPosMult.Add(cur, MultSymbolsFromPosToPos(seq, prev, cur - 1));
                }

                foreach (var pI in possibleIPos)
                {
                    possibleKPos = possibleKPos.Where(pK => pK > (pI + 1)).ToList();
                    if (!possibleKPos.Any())
                    {
                        break;
                    }

                    int prevPK   = possibleKPos[0];
                    int prevMult = MultSymbolsFromPosToPos(seq, pI + 1, prevPK - 1);

                    if (prevMult == Symb.j)
                    {
                        return("YES");
                    }

                    foreach (var pK in possibleKPos.Skip(1).ToList())
                    {
                        prevMult = Symb.Mult(prevMult, nextKPosMult[pK]);
                        if (prevMult == Symb.j)
                        {
                            return("YES");
                        }
                    }
                }
                return("NO");
            }
            else if (r > 1)
            {
                int cf = MultSymbolsFromPosToPos(seq, 0, seq.Length - 1);

                //long newR = r % 4;
                long newR = Math.Min((r % 4) + 16, r);

                //for (var newR = (int)(r % 4); newR <= r && newR <= 100; newR += 4)
                //{
                for (var i = 0; i < newR; i++)
                {
                    int cfpi = Symb.Power(cf, i);
                    for (var k = i; k < newR; k++)
                    {
                        int cfpk = Symb.Power(cf, (int)(newR - 1 - k));
                        int cfpj = Symb.Power(cf, k - i - 1);
                        if (Solve(new Tuple <long, int[]>(1, Merge(seq, cfpi, cfpk, cfpj, k == i))) == "YES")
                        {
                            return("YES");
                        }
                    }
                }
                //}
                return("NO");
            }
            else
            {
                throw new NotImplementedException();
            }
        }