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ABC460-D Repeatedly Repainting


問題へのリンク


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("3 4");
            WillReturn.Add("#.#.");
            WillReturn.Add(".#..");
            WillReturn.Add("#...");
            //#.#.
            //.#..
            //#..#
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("3 3");
            WillReturn.Add("###");
            WillReturn.Add("###");
            WillReturn.Add("###");
            //...
            //...
            //...
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("5 7");
            WillReturn.Add(".#.....");
            WillReturn.Add(".......");
            WillReturn.Add("..#....");
            WillReturn.Add(".......");
            WillReturn.Add("....#..");
            //.#.##.#
            //....#..
            //#.#.###
            //#.....#
            //###.#.#
        }
        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();
    }

    static int UB_X;
    static int UB_Y;

    static void Main()
    {
        List<string> InputList = GetInputList();
        char[,] BanArr = CreateBanArr(InputList.Skip(1));
        UB_X = BanArr.GetUpperBound(0);
        UB_Y = BanArr.GetUpperBound(1);

        // 初回だけ、特殊な変化をするので、2回変化させる
        BanArr = GetChange(BanArr);
        BanArr = GetChange(BanArr);

        long[,] DistanceArr = new long[UB_X + 1, UB_Y + 1];
        for (int X = 0; X <= UB_X; X++) {
            for (int Y = 0; Y <= UB_Y; Y++) {
                DistanceArr[X, Y] = long.MaxValue;
            }
        }

        // 全部白の場合
        bool HasBlack = false;
        for (int X = 0; X <= UB_X; X++) {
            for (int Y = 0; Y <= UB_Y; Y++) {
                if (BanArr[X, Y] == '#') {
                    HasBlack = true;
                }
            }
        }
        if (HasBlack == false) {
            PrintBan(BanArr);
            return;
        }

        // 多始点BFS
        var Que = new Queue<JyoutaiDef>();
        JyoutaiDef WillEnqueue;
        for (int X = 0; X <= UB_X; X++) {
            for (int Y = 0; Y <= UB_Y; Y++) {
                if (BanArr[X, Y] == '#') {
                    DistanceArr[X, Y] = 0;
                    WillEnqueue.CurrX = X;
                    WillEnqueue.CurrY = Y;
                    WillEnqueue.Level = 0;
                    Que.Enqueue(WillEnqueue);
                }
            }
        }

        while (Que.Count > 0) {
            JyoutaiDef Dequeued = Que.Dequeue();

            PointDef[] PosArr = Get8KinbouPosArr(Dequeued.CurrX, Dequeued.CurrY, 0, UB_X, 0, UB_Y);

            foreach (PointDef EachPos in PosArr) {
                if (DistanceArr[EachPos.X, EachPos.Y] < long.MaxValue) {
                    continue;
                }
                DistanceArr[EachPos.X, EachPos.Y] = Dequeued.Level + 1;
                WillEnqueue.CurrX = EachPos.X;
                WillEnqueue.CurrY = EachPos.Y;
                WillEnqueue.Level = Dequeued.Level + 1;
                Que.Enqueue(WillEnqueue);
            }
        }

        for (int Y = 0; Y <= UB_Y; Y++) {
            for (int X = 0; X <= UB_X; X++) {
                if (DistanceArr[X, Y] % 2 == 0) {
                    Console.Write('#');
                }
                else {
                    Console.Write('.');
                }
            }
            Console.WriteLine();
        }
    }

    struct JyoutaiDef
    {
        internal long CurrX;
        internal long CurrY;
        internal long Level;
    }

    // 変換処理を行う
    static char[,] GetChange(char[,] pBeforeBanArr)
    {
        char[,] NewBanArr = new char[UB_X + 1, UB_Y + 1];

        for (int X = 0; X <= UB_X; X++) {
            for (int Y = 0; Y <= UB_Y; Y++) {
                if (pBeforeBanArr[X, Y] == '.') {
                    if (HasBlack(X, Y, pBeforeBanArr)) {
                        NewBanArr[X, Y] = '#';
                    }
                    else {
                        NewBanArr[X, Y] = '.';
                    }
                }
                else if (pBeforeBanArr[X, Y] == '#') {
                    NewBanArr[X, Y] = '.';
                }
            }
        }
        return NewBanArr;
    }

    // 8近傍に黒があるかを返す
    static bool HasBlack(int pBaseX, int pBaseY, char[,] pBeforeBanArr)
    {
        PointDef[] PosArr = Get8KinbouPosArr(pBaseX, pBaseY, 0, UB_X, 0, UB_Y);
        if (Array.Exists(PosArr, pX => pBeforeBanArr[pX.X, pX.Y] == '#')) {
            return true;
        }
        return false;
    }

    ////////////////////////////////////////////////////////////////
    // IEnumerable<string>をcharの2次元配列に設定
    ////////////////////////////////////////////////////////////////
    static char[,] CreateBanArr(IEnumerable<string> pStrEnum)
    {
        var StrList = pStrEnum.ToList();
        if (StrList.Count == 0) {
            return new char[0, 0];
        }
        int UB_X = StrList[0].Length - 1;
        int UB_Y = StrList.Count - 1;

        char[,] WillReturn = new char[UB_X + 1, UB_Y + 1];

        for (int Y = 0; Y <= UB_Y; Y++) {
            for (int X = 0; X <= UB_X; X++) {
                WillReturn[X, Y] = StrList[Y][X];
            }
        }
        return WillReturn;
    }

    ////////////////////////////////////////////////////////////////
    // 2次元配列(char型)のデバッグ出力
    ////////////////////////////////////////////////////////////////
    static void PrintBan(char[,] pBanArr)
    {
        var sb = new System.Text.StringBuilder();
        for (int Y = 0; Y <= pBanArr.GetUpperBound(1); Y++) {
            for (int X = 0; X <= pBanArr.GetUpperBound(0); X++) {
                sb.Append(pBanArr[X, Y]);
            }
            sb.AppendLine();
        }
        Console.Write(sb.ToString());
    }

    ////////////////////////////////////////////////////////////////
    // 座標の構造体
    ////////////////////////////////////////////////////////////////
    struct PointDef
    {
        internal long X;
        internal long Y;
    }

    ////////////////////////////////////////////////////////////////
    // グリッドの4近傍の座標の配列を返す
    ////////////////////////////////////////////////////////////////
    static PointDef[] Get4KinbouPosArr(long pBaseX, long pBaseY,
                                       long pMinX, long pMaxX,
                                       long pMinY, long pMaxY)
    {
        var WillReturn = new List<PointDef>();

        Action<long, long> AddAct = (pTargetX, pTargetY) =>
        {
            if (pTargetX < 0 || pMaxX < pTargetX) return;
            if (pTargetY < 0 || pMaxY < pTargetY) return;

            WillReturn.Add(new PointDef() { X = pTargetX, Y = pTargetY });
        };

        AddAct(pBaseX - 1, pBaseY - 1);
        AddAct(pBaseX - 1, pBaseY + 1);
        AddAct(pBaseX + 1, pBaseY - 1);
        AddAct(pBaseX + 1, pBaseY + 1);

        return WillReturn.ToArray();
    }

    ////////////////////////////////////////////////////////////////
    // グリッドの8近傍の座標の配列を返す
    ////////////////////////////////////////////////////////////////
    static PointDef[] Get8KinbouPosArr(long pBaseX, long pBaseY,
                                       long pMinX, long pMaxX,
                                       long pMinY, long pMaxY)
    {
        var WillReturn = new List<PointDef>();

        Action<long, long> AddAct = (pTargetX, pTargetY) =>
        {
            if (pTargetX < 0 || pMaxX < pTargetX) return;
            if (pTargetY < 0 || pMaxY < pTargetY) return;

            WillReturn.Add(new PointDef() { X = pTargetX, Y = pTargetY });
        };

        AddAct(pBaseX - 1, pBaseY - 1);
        AddAct(pBaseX - 1, pBaseY);
        AddAct(pBaseX - 1, pBaseY + 1);

        AddAct(pBaseX, pBaseY - 1);
        AddAct(pBaseX, pBaseY + 1);

        AddAct(pBaseX + 1, pBaseY - 1);
        AddAct(pBaseX + 1, pBaseY);
        AddAct(pBaseX + 1, pBaseY + 1);

        return WillReturn.ToArray();
    }
}


解説

ダイソーのオセロセットで考察すると
10の100乗回操作するので、
10の100乗回後の白黒は、
黒からの距離の偶奇で決まると分かります。

初回だけ、特殊な変化をするので、2回変化させてから
多始点BFSで、黒マスからのキング距離を求めれば良いとも分かります。