ABC436-D Teleport Maze

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("..a.");
            WillReturn.Add("####");
            WillReturn.Add("ba#b");
            //5
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("3 4");
            WillReturn.Add("..a.");
            WillReturn.Add("####");
            WillReturn.Add("b.#b");
            //-1
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("4 4");
            WillReturn.Add("xxxx");
            WillReturn.Add("xxxx");
            WillReturn.Add("xxxx");
            WillReturn.Add("xxxx");
            //1
        }
        else if (InputPattern == "Input4") {
            WillReturn.Add("7 11");
            WillReturn.Add("u..#y..#...");
            WillReturn.Add("k..#.z.#.k.");
            WillReturn.Add("iju#...#x..");
            WillReturn.Add("###########");
            WillReturn.Add("..x#.t.#..n");
            WillReturn.Add("abc#y..#...");
            WillReturn.Add("..z#..t#.y.");
            //12
        }
        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 void Main()
    {
        List<string> InputList = GetInputList();
        char[,] BanArr = CreateBanArr(InputList.Skip(1));

        int UB_X = BanArr.GetUpperBound(0);
        int UB_Y = BanArr.GetUpperBound(1);

        // 座標のList[文字]なDict
        var PosListDict = new Dictionary<char, List<PointDef>>();
        for (int X = 0; X <= UB_X; X++) {
            for (int Y = 0; Y <= UB_Y; Y++) {
                char CurrChar = BanArr[X, Y];
                if ('a' <= CurrChar && CurrChar <= 'z') {
                    if (PosListDict.ContainsKey(CurrChar) == false) {
                        PosListDict[CurrChar] = new List<PointDef>();
                    }
                    PointDef WillAdd;
                    WillAdd.X = X;
                    WillAdd.Y = Y;
                    PosListDict[CurrChar].Add(WillAdd);
                }
            }
        }

        var Que = new Queue<JyoutaiDef>();
        JyoutaiDef WillEnqueue;
        WillEnqueue.CurrX = 0;
        WillEnqueue.CurrY = 0;
        WillEnqueue.Level = 0;
        Que.Enqueue(WillEnqueue);

        var VisitedSet = new HashSet<int>();

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

            // クリア判定
            if (Dequeued.CurrX == UB_X && Dequeued.CurrY == UB_Y) {
                Console.WriteLine(Dequeued.Level);
                return;
            }

            // ワープで移動
            char CurrChar = BanArr[Dequeued.CurrX, Dequeued.CurrY];
            if (PosListDict.ContainsKey(CurrChar)) {
                foreach (PointDef EachPos in PosListDict[CurrChar]) {
                    WillEnqueue.CurrX = EachPos.X;
                    WillEnqueue.CurrY = EachPos.Y;
                    WillEnqueue.Level = Dequeued.Level + 1;

                    int Hash = GetHash(EachPos.X, EachPos.Y);
                    if (VisitedSet.Add(Hash)) {
                        Que.Enqueue(WillEnqueue);
                    }
                }
                // 今後はワープ不可
                PosListDict.Remove(CurrChar);
            }

            // 4近傍に移動
            Action<int, int> MoveAct = (pNewX, pNewY) =>
            {
                if (pNewX < 0 || UB_X < pNewX) return;
                if (pNewY < 0 || UB_Y < pNewY) return;

                if (BanArr[pNewX, pNewY] == '#') return;
                WillEnqueue.CurrX = pNewX;
                WillEnqueue.CurrY = pNewY;
                WillEnqueue.Level = Dequeued.Level + 1;

                int Hash = GetHash(pNewX, pNewY);
                if (VisitedSet.Add(Hash)) {
                    Que.Enqueue(WillEnqueue);
                }
            };
            MoveAct(Dequeued.CurrX, Dequeued.CurrY - 1);
            MoveAct(Dequeued.CurrX, Dequeued.CurrY + 1);
            MoveAct(Dequeued.CurrX - 1, Dequeued.CurrY);
            MoveAct(Dequeued.CurrX + 1, Dequeued.CurrY);
        }

        Console.WriteLine(-1);
    }

    static int GetHash(int pX, int pY)
    {
        int Hash = 0;
        Hash += pX;
        Hash *= 10000;
        Hash += pY;
        return Hash;
    }

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

    struct PointDef
    {
        internal int X;
        internal int Y;
    }

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

解説

ダイソーのオセロセットで下記の盤面を考えます。
(黒は移動不可マス、白はワープマス)

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この問題の制約では、H*W は最大で1000*1000なので
黒の45度ラインが長いことを考慮し、
TLE対策で、全体のBFSで、ワープは文字ごとに最小レベルで1回のみ使用可します。

これは、Dict.remove(該当文字)で実現できますし、
Dict[該当文字].Clearでも実現できます。