AOJ 0692 パンケーキ

問題へのリンク(AOJ)
問題へのリンク(AtCoder)

C#のソース

using System;
using System.Collections.Generic;
using System.Linq;

class Program
{
    static string InputPattern = "InputX";

    static List<string> GetInputList()
    {
        var WillReturn = new List<string>();

        if (InputPattern == "Input1") {
            WillReturn.Add("5 3");
            WillReturn.Add("ABCBA");
            WillReturn.Add("CCBAB");
            WillReturn.Add("AAAAA");
            //3
            //2
            //0
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("2 5");
            WillReturn.Add("AC");
            WillReturn.Add("AC");
            WillReturn.Add("AC");
            WillReturn.Add("AC");
            WillReturn.Add("AC");
            //0
            //0
            //0
            //0
            //0
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("13 1");
            WillReturn.Add("ABCCABCBACBAA");
            //9
        }
        else if (InputPattern == "Input4") {
            WillReturn.Add("13 4");
            WillReturn.Add("CCAAACBAAAABB");
            WillReturn.Add("BBBCCBCCCBCBC");
            WillReturn.Add("CCCAAAABBBBBB");
            WillReturn.Add("AABCBCACBACBA");
            //4
            //6
            //2
            //10
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static long[] GetSplitArr(string pStr)
    {
        return (pStr == "" ? new string[0] : pStr.Split(' ')).Select(pX => long.Parse(pX)).ToArray();
    }

    // 10べき[指数]
    static Dictionary<long, long> mBeki10Dict = new Dictionary<long, long>();

    // 最上位の10べきを返す
    static long DeriveTopBeki10(long pVal)
    {
        for (long I = 17; 0 <= I; I--) {
            if (pVal >= mBeki10Dict[I]) {
                return mBeki10Dict[I];
            }
        }
        return 1;
    }

    static void Main()
    {
        long Beki10 = 1;
        for (long I = 0; I <= 17; I++) {
            mBeki10Dict[I] = Beki10;
            Beki10 *= 10;
        }

        List<string> InputList = GetInputList();

        var StrSet = new HashSet<string>();
        StrSet.UnionWith(InputList.Skip(1));

        var GoodStrSet = new HashSet<string>();
        foreach (string EachStr in StrSet) {
            string GoodStr = DeriveGoodStr(EachStr);
            GoodStrSet.Add(GoodStr);
        }

        // 多始点BFS
        var Que = new Queue<JyoutaiDef>();
        JyoutaiDef WillEnqueue;
        foreach (string EachStr in GoodStrSet) {
            WillEnqueue.CurrVal = GetNum(EachStr);
            WillEnqueue.Level = 0;
            Que.Enqueue(WillEnqueue);

            long GoodNum = GetNum(EachStr);
            mMemo[GoodNum] = 0;
        }
        while (Que.Count > 0) {
            JyoutaiDef Dequeued = Que.Dequeue();

            long TopBeki10 = DeriveTopBeki10(Dequeued.CurrVal);
            for (long I = TopBeki10 / 10; 1 <= I; I /= 10) {
                long NewVal = ExecShift(Dequeued.CurrVal, TopBeki10, I);
                WillEnqueue.CurrVal = NewVal;
                WillEnqueue.Level = Dequeued.Level + 1;
                if (mMemo.ContainsKey(WillEnqueue.CurrVal)) {
                    if (mMemo[WillEnqueue.CurrVal] <= WillEnqueue.Level) {
                        continue;
                    }
                }
                mMemo[WillEnqueue.CurrVal] = WillEnqueue.Level;
                Que.Enqueue(WillEnqueue);
            }
        }

        var sb = new System.Text.StringBuilder();
        foreach (string EachStr in InputList.Skip(1)) {
            long Result = mMemo[GetNum(EachStr)];
            sb.Append(Result);
            sb.AppendLine();
        }
        Console.Write(sb.ToString());
    }

    static Dictionary<long, long> mMemo = new Dictionary<long, long>();

    struct JyoutaiDef
    {
        internal long CurrVal;
        internal long Level;
    }

    // 文字列を引数とし、良いパンケーキタワーな文字列を返す
    static string DeriveGoodStr(string pStr)
    {
        char[] CharArr = pStr.ToCharArray();
        int ACnt = CharArr.Count(pX => pX == 'A');
        int BCnt = CharArr.Count(pX => pX == 'B');
        int CCnt = CharArr.Count(pX => pX == 'C');

        var sb = new System.Text.StringBuilder();
        sb.Append(new string('A', ACnt));
        sb.Append(new string('B', BCnt));
        sb.Append(new string('C', CCnt));
        return sb.ToString();
    }

    // Aを1、Bを2、Cを3に変換した数値を返す
    static long GetNum(string pStr)
    {
        long WillReturn = 0;
        long Omomi = 1;
        for (int I = pStr.Length - 1; 0 <= I; I--) {
            if (pStr[I] == 'A') WillReturn += Omomi * 1;
            if (pStr[I] == 'B') WillReturn += Omomi * 2;
            if (pStr[I] == 'C') WillReturn += Omomi * 3;
            Omomi *= 10;
        }
        return WillReturn;
    }

    // long型で、先頭桁の回転を行う
    static long ExecShift(long pTargetVal, long pStaShisuu, long pEndShisuu)
    {
        while (pStaShisuu > pEndShisuu) {
            long Num1 = (pTargetVal / pStaShisuu) % 10;
            long Num2 = (pTargetVal / pEndShisuu) % 10;

            pTargetVal += (Num2 - Num1) * pStaShisuu;
            pTargetVal += (Num1 - Num2) * pEndShisuu;

            pStaShisuu /= 10;
            pEndShisuu *= 10;
        }
        return pTargetVal;
    }
}

解説

文字列が決まれば、良いパンケーキタワーな文字列は一意に決定します。

なのでクエリを全て先読みしてから、
良いパンケーキタワーからの逆方向のBFSを、多始点で行ってます。

定数倍改善でlong型のままで、先頭数字の回転を行ってます。