ABC424-D 2x2 Erasing 2

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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("2");
            WillReturn.Add("5 5");
            WillReturn.Add("####.");
            WillReturn.Add("##.##");
            WillReturn.Add("#####");
            WillReturn.Add(".####");
            WillReturn.Add("##.#.");
            WillReturn.Add("2 2");
            WillReturn.Add("..");
            WillReturn.Add("..");
            //3
            //0
        }
        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 char[,] mBanArr;
    static long UB_X;
    static long UB_Y;

    static void Main()
    {
        List<string> InputList = GetInputList();
        int CurrInd = 1;

        long[] wkArr = { };
        Action<string> SplitAct = (pStr) => wkArr = GetSplitArr(pStr);

        var sb = new System.Text.StringBuilder();
        while (true) {
            if (CurrInd > InputList.Count - 1) break;
            SplitAct(InputList[CurrInd]);
            long H = wkArr[0];
            long W = wkArr[1];

            mBanArr = CreateBanArr(InputList.Skip(CurrInd + 1).Take((int)H));

            long Answer = Solve();
            sb.Append(Answer);
            sb.AppendLine();

            CurrInd += (int)H + 1;
        }
        Console.Write(sb.ToString());
    }

    static long Solve()
    {
        UB_X = mBanArr.GetUpperBound(0);
        UB_Y = mBanArr.GetUpperBound(1);

        var InsLinkedList = new LinkedList<JyoutaiDef>();
        JyoutaiDef WillEnqueue;
        WillEnqueue.CurrX = 0;
        WillEnqueue.CurrY = 0;
        WillEnqueue.BanArr = mBanArr;
        WillEnqueue.Val = 0;
        InsLinkedList.AddFirst(WillEnqueue);

        long Answer = long.MaxValue;
        while (InsLinkedList.Count > 0) {
            JyoutaiDef Dequeued = InsLinkedList.First.Value;
            InsLinkedList.RemoveFirst();

            if (Dequeued.CurrX > UB_X) {
                Dequeued.CurrX = 0;
                Dequeued.CurrY++;
            }

            // クリア判定
            if (Dequeued.CurrY == UB_Y) {
                Answer = Math.Min(Answer, Dequeued.Val);
                continue;
            }
            if (Answer <= Dequeued.Val) continue;

            long CurrX = Dequeued.CurrX;
            long CurrY = Dequeued.CurrY;

            // 2*2が黒かを判定
            if (Is_2_2_Black(CurrX, CurrY, Dequeued.BanArr)) {
                // 左下を白にする
                WillEnqueue.CurrX = Dequeued.CurrX + 1;
                WillEnqueue.CurrY = Dequeued.CurrY;
                WillEnqueue.BanArr = (char[,])Dequeued.BanArr.Clone();
                WillEnqueue.BanArr[CurrX, CurrY + 1] = '.';
                WillEnqueue.Val = Dequeued.Val + 1;
                InsLinkedList.AddLast(WillEnqueue);

                // 右下を白にする
                WillEnqueue.CurrX = Dequeued.CurrX + 1 + 1;
                WillEnqueue.CurrY = Dequeued.CurrY;
                WillEnqueue.BanArr = (char[,])Dequeued.BanArr.Clone();
                WillEnqueue.BanArr[CurrX + 1, CurrY + 1] = '.';
                WillEnqueue.Val = Dequeued.Val + 1;
                InsLinkedList.AddLast(WillEnqueue);
            }
            else {
                // カレントの移動
                WillEnqueue.CurrX = Dequeued.CurrX + 1;
                WillEnqueue.CurrY = Dequeued.CurrY;
                WillEnqueue.BanArr = Dequeued.BanArr;
                WillEnqueue.Val = Dequeued.Val;
                InsLinkedList.AddFirst(WillEnqueue);
            }
        }
        return Answer;
    }

    // 2*2が黒かを判定
    static bool Is_2_2_Black(long pBaseX, long pBaseY, char[,] pBanArr)
    {
        if (pBaseX + 1 > UB_X) return false;
        if (pBaseY + 1 > UB_Y) return false;

        if (pBanArr[pBaseX, pBaseY] == '.') return false;
        if (pBanArr[pBaseX, pBaseY + 1] == '.') return false;
        if (pBanArr[pBaseX + 1, pBaseY] == '.') return false;
        if (pBanArr[pBaseX + 1, pBaseY + 1] == '.') return false;
        return true;
    }

    ////////////////////////////////////////////////////////////////
    // 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;
    }

    struct JyoutaiDef
    {
        internal long CurrX;
        internal long CurrY;
        internal char[,] BanArr;
        internal long Val;
    }
}

解説

オセロセットで考察し、下記で解いてます。

{CurrX,CurrY,盤面の二次元配列,コスト}を状態に持つ。
座標をZ順で見ていき、2*2の黒マスがあったら、左下と右下の変更を両方試す。
コストは0と1の2通りしかないため、01BFS。