典型90問 043 Maze Challenge with Lack of Sleep（★4）

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 3");
            WillReturn.Add("1 1");
            WillReturn.Add("3 3");
            WillReturn.Add("..#");
            WillReturn.Add("#.#");
            WillReturn.Add("#..");
            //2
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("3 3");
            WillReturn.Add("2 1");
            WillReturn.Add("2 3");
            WillReturn.Add("#.#");
            WillReturn.Add("...");
            WillReturn.Add("#.#");
            //0
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("4 6");
            WillReturn.Add("2 1");
            WillReturn.Add("1 5");
            WillReturn.Add("...#..");
            WillReturn.Add(".#.##.");
            WillReturn.Add(".#....");
            WillReturn.Add("...##.");
            //5
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static int mSta_Y;
    static int mSta_X;
    static int mGoal_Y;
    static int mGoal_X;

    static char[,] mBanArr;
    static int UB_X;
    static int UB_Y;

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

        int[] wkArr = { };
        Action<string> SplitAct = pStr =>
            wkArr = pStr.Split(' ').Select(pX => int.Parse(pX)).ToArray();

        SplitAct(InputList[1]);
        mSta_Y = wkArr[0] - 1;
        mSta_X = wkArr[1] - 1;

        SplitAct(InputList[2]);
        mGoal_Y = wkArr[0] - 1;
        mGoal_X = wkArr[1] - 1;

        mBanArr = CreateBanArr(InputList.Skip(3));
        UB_X = mBanArr.GetUpperBound(0);
        UB_Y = mBanArr.GetUpperBound(1);

        ExecBFS();
    }

    struct JyoutaiDef
    {
        internal int Vect_X;
        internal int Vect_Y;
        internal int Curr_X;
        internal int Curr_Y;
        internal int Cost;
        internal int Level;
    }

    static void ExecBFS()
    {
        var InsLinkedList = new LinkedList<JyoutaiDef>();
        JyoutaiDef WillEnque;
        WillEnque.Vect_X = 0;
        WillEnque.Vect_Y = 0;
        WillEnque.Curr_X = mSta_X;
        WillEnque.Curr_Y = mSta_Y;
        WillEnque.Cost = 0;
        WillEnque.Level = 0;
        InsLinkedList.AddFirst(WillEnque);

        // 最小コスト[座標のハッシュ値]
        var EdakiriDict = new Dictionary<int, int>();

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

            if (Dequeued.Curr_X == mGoal_X && Dequeued.Curr_Y == mGoal_Y) {
                Console.WriteLine(Dequeued.Cost);
                break;
            }

            Action<int, int> EnqueuAct = (pVect_X, pVect_Y) =>
            {
                // 逆ベクトルは不可
                int Rev_X = Dequeued.Vect_X * (-1);
                int Rev_Y = Dequeued.Vect_Y * (-1);
                if (pVect_X == Rev_X && pVect_Y == Rev_Y) {
                    return;
                }

                int NewX = Dequeued.Curr_X + pVect_X;
                int NewY = Dequeued.Curr_Y + pVect_Y;
                if (NewX < 0 || UB_X < NewX) return;
                if (NewY < 0 || UB_Y < NewY) return;

                if (mBanArr[NewX, NewY] == '#') return;

                bool AddCost = false;
                if (Dequeued.Level > 0) {
                    if (Dequeued.Vect_X != pVect_X || Dequeued.Vect_Y != pVect_Y) {
                        AddCost = true;
                    }
                }

                WillEnque.Vect_X = pVect_X;
                WillEnque.Vect_Y = pVect_Y;
                WillEnque.Curr_X = NewX;
                WillEnque.Curr_Y = NewY;
                WillEnque.Cost = Dequeued.Cost;
                WillEnque.Level = Dequeued.Level + 1;

                if (AddCost) {
                    WillEnque.Cost++;
                }

                int Hash = GetHash(WillEnque.Curr_X, WillEnque.Curr_Y);
                if (EdakiriDict.ContainsKey(Hash)) {
                    // ベクトルが違う可能性があるので、
                    // 等しい場合は許可だが、真に大きい場合は不可
                    if (EdakiriDict[Hash] < WillEnque.Cost) {
                        return;
                    }
                }
                EdakiriDict[Hash] = WillEnque.Cost;

                if (AddCost) {
                    InsLinkedList.AddLast(WillEnque);
                }
                else {
                    InsLinkedList.AddFirst(WillEnque);
                }
            };
            EnqueuAct(0, -1);
            EnqueuAct(0, +1);
            EnqueuAct(-1, 0);
            EnqueuAct(+1, 0);
        }
    }

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

    ////////////////////////////////////////////////////////////////
    // IEnumerable<string>をcharの2次元配列に設定する
    ////////////////////////////////////////////////////////////////
    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

01BFSで、枝切りも付けてます。