ABC387-D Snaky Walk

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 5");
            WillReturn.Add(".S#.G");
            WillReturn.Add(".....");
            WillReturn.Add(".#...");
            //7
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("3 5");
            WillReturn.Add("..#.G");
            WillReturn.Add(".....");
            WillReturn.Add("S#...");
            //-1
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("8 63");
            WillReturn.Add("...............................................................");
            WillReturn.Add("..S...#............................#####..#####..#####..####G..");
            WillReturn.Add("..#...#................................#..#...#......#..#......");
            WillReturn.Add("..#####..####...####..####..#..#...#####..#...#..#####..#####..");
            WillReturn.Add("..#...#..#..#...#..#..#..#..#..#...#......#...#..#..........#..");
            WillReturn.Add("..#...#..#####..####..####..####...#####..#####..#####..#####..");
            WillReturn.Add("................#.....#........#...............................");
            WillReturn.Add("................#.....#........#...............................");
            //148
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static char[,] mBanArr;
    static int UB_X;
    static int UB_Y;
    static int StaX;
    static int StaY;
    static int GoalX;
    static int GoalY;

    static void Main()
    {
        List<string> InputList = GetInputList();
        mBanArr = CreateBanArr(InputList.Skip(1));
        UB_X = mBanArr.GetUpperBound(0);
        UB_Y = mBanArr.GetUpperBound(1);

        for (int X = 0; X <= UB_X; X++) {
            for (int Y = 0; Y <= UB_Y; Y++) {
                if (mBanArr[X, Y] == 'S') {
                    StaX = X; StaY = Y;
                }
                if (mBanArr[X, Y] == 'G') {
                    GoalX = X; GoalY = Y;
                }
            }
        }

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

        WillEnqueue.CurrX = StaX;
        WillEnqueue.CurrY = StaY;
        WillEnqueue.MoveTate = 1;
        WillEnqueue.Level = 0;
        Que.Enqueue(WillEnqueue);

        var VisitedSet = new HashSet<long>();
        while (Que.Count > 0) {
            JyoutaiDef Dequeued = Que.Dequeue();

            if (Dequeued.CurrX == GoalX && Dequeued.CurrY == GoalY) {
                Console.WriteLine(Dequeued.Level);
                return;
            }

            Action<int, int, int> EnqueueAct = (pNewX, pNewY, pMoveTate) =>
            {
                if (pNewX < 0 || UB_X < pNewX) return;
                if (pNewY < 0 || UB_Y < pNewY) return;

                if (mBanArr[pNewX, pNewY] == '#') return;

                long Hash = GetHash(pNewX, pNewY, pMoveTate);
                if (VisitedSet.Add(Hash)) {
                    WillEnqueue.CurrX = pNewX;
                    WillEnqueue.CurrY = pNewY;
                    WillEnqueue.MoveTate = pMoveTate;
                    WillEnqueue.Level = Dequeued.Level + 1;
                    Que.Enqueue(WillEnqueue);
                }
            };

            int MoveTate = Dequeued.MoveTate;
            if (MoveTate == 1) {
                EnqueueAct(Dequeued.CurrX, Dequeued.CurrY - 1, 0);
                EnqueueAct(Dequeued.CurrX, Dequeued.CurrY + 1, 0);
            }
            else {
                EnqueueAct(Dequeued.CurrX - 1, Dequeued.CurrY, 1);
                EnqueueAct(Dequeued.CurrX + 1, Dequeued.CurrY, 1);
            }
        }
        Console.WriteLine(-1);
    }

    static long GetHash(int pX, int pY, int pMoveTate)
    {
        long Hash = 0;
        Hash += pX;

        Hash *= 10000;
        Hash += pY;

        Hash *= 10;
        Hash += pMoveTate;

        return Hash;
    }

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

    ////////////////////////////////////////////////////////////////
    // 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

{X,Y,縦移動か？}で再訪防止のBFSをしてます。