第11回PAST N 壁の建設計画

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("2 3");
            WillReturn.Add("0 6 4");
            WillReturn.Add("2 3 0");
            //7
            //..#
            //.#.
        }
        else if (InputPattern == "Input2") {
            WillReturn.Add("4 3");
            WillReturn.Add("0 9 2");
            WillReturn.Add("9 3 9");
            WillReturn.Add("2 3 9");
            WillReturn.Add("3 9 0");
            //7
            //..#
            //.#.
            //#..
            //...
        }
        else if (InputPattern == "Input3") {
            WillReturn.Add("2 2");
            WillReturn.Add("0 1000000000");
            WillReturn.Add("1000000000 0");
            //2000000000
            //.#
            //#.
        }
        else {
            string wkStr;
            while ((wkStr = Console.ReadLine()) != null) WillReturn.Add(wkStr);
        }
        return WillReturn;
    }

    static long UB_X;
    static long UB_Y;

    static void Main()
    {
        List<string> InputList = GetInputList();
        long[] wkArr = InputList[0].Split(' ').Select(pX => long.Parse(pX)).ToArray();
        UB_Y = wkArr[0] - 1;
        UB_X = wkArr[1] - 1;

        long[,] CostArr = CreateBanArr(InputList.Skip(1));
        long?[,] MinCostArr = new long?[UB_X + 1, UB_Y + 1];
        long?[,] ParentNodeArr = new long?[UB_X + 1, UB_Y + 1];

        var InsPQueue_Arr = new PQueue_Arr();
        PQueue_Arr.PQueueJyoutaiDef WillEnqueue;

        for (long X = 1; X <= UB_X; X++) {
            WillEnqueue.CurrX = X;
            WillEnqueue.CurrY = 0;
            WillEnqueue.Val = CostArr[X, 0];
            InsPQueue_Arr.Enqueue(WillEnqueue);

            MinCostArr[X, 0] = CostArr[X, 0];
        }
        for (long Y = 0; Y <= UB_Y - 1; Y++) {
            WillEnqueue.CurrX = UB_X;
            WillEnqueue.CurrY = Y;
            WillEnqueue.Val = CostArr[UB_X, Y];
            InsPQueue_Arr.Enqueue(WillEnqueue);

            MinCostArr[UB_X, Y] = CostArr[UB_X, Y];
        }

        long Answer = long.MaxValue;
        long GoalX = -1;
        long GoalY = -1;
        while (InsPQueue_Arr.Count() > 0) {
            PQueue_Arr.PQueueJyoutaiDef Dequeued = InsPQueue_Arr.Dequeue();

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

            // クリア判定
            if (CurrX == 0 || CurrY == UB_Y) {
                Answer = Math.Min(Answer, Dequeued.Val);
                GoalX = CurrX;
                GoalY = CurrY;
                break;
            }

            List<PointDef> KinbouList = Get8KinbouList(CurrX, CurrY);
            foreach (PointDef EachPoint in KinbouList) {
                if (EachPoint.X == 0 && EachPoint.Y == 0) continue;
                if (EachPoint.X == UB_X && EachPoint.Y == UB_Y) continue;

                long NewCost = Dequeued.Val + CostArr[EachPoint.X, EachPoint.Y];
                if (MinCostArr[EachPoint.X, EachPoint.Y].HasValue) {
                    if (NewCost >= MinCostArr[EachPoint.X, EachPoint.Y].Value) {
                        continue;
                    }
                }
                MinCostArr[EachPoint.X, EachPoint.Y] = NewCost;

                long ParentHash = GetHash(CurrX, CurrY);
                ParentNodeArr[EachPoint.X, EachPoint.Y] = ParentHash;

                WillEnqueue.CurrX = EachPoint.X;
                WillEnqueue.CurrY = EachPoint.Y;
                WillEnqueue.Val = NewCost;
                InsPQueue_Arr.Enqueue(WillEnqueue);
            }
        }
        Console.WriteLine(Answer);

        char[,] AnswerArr = new char[UB_X + 1, UB_Y + 1];
        for (long X = 0; X <= UB_X; X++) {
            for (long Y = 0; Y <= UB_Y; Y++) {
                AnswerArr[X, Y] = '.';
            }
        }

        while (true) {
            AnswerArr[GoalX, GoalY] = '#';
            if (ParentNodeArr[GoalX, GoalY].HasValue) {
                long ParentHash = ParentNodeArr[GoalX, GoalY].Value;
                GoalX = ParentHash / 1000;
                GoalY = ParentHash % 1000;
            }
            else break;
        }
        PrintBan(AnswerArr);
    }

    // 座標のハッシュ値
    static long GetHash(long pX, long pY)
    {
        return pX * 1000 + pY;
    }

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

    // 8近傍の座標を返す
    static List<PointDef> Get8KinbouList(long pX, long pY)
    {
        var WillReturn = new List<PointDef>();
        WillReturn.AddRange(GetPoint(pX - 1, pY - 1));
        WillReturn.AddRange(GetPoint(pX + 0, pY - 1));
        WillReturn.AddRange(GetPoint(pX + 1, pY - 1));

        WillReturn.AddRange(GetPoint(pX - 1, pY + 0));
        WillReturn.AddRange(GetPoint(pX + 1, pY + 0));

        WillReturn.AddRange(GetPoint(pX - 1, pY + 1));
        WillReturn.AddRange(GetPoint(pX + 0, pY + 1));
        WillReturn.AddRange(GetPoint(pX + 1, pY + 1));

        return WillReturn;
    }

    static List<PointDef> GetPoint(long pTargetX, long pTargetY)
    {
        var WillReturn = new List<PointDef>();
        if (pTargetX < 0 || UB_X < pTargetX) return WillReturn;
        if (pTargetY < 0 || UB_Y < pTargetY) return WillReturn;

        PointDef WillAdd;
        WillAdd.X = pTargetX;
        WillAdd.Y = pTargetY;
        WillReturn.Add(WillAdd);
        return WillReturn;
    }

    ////////////////////////////////////////////////////////////////
    // IEnumerable<string>をlongの2次元配列に設定
    ////////////////////////////////////////////////////////////////
    static long[,] CreateBanArr(IEnumerable<string> pStrEnum)
    {
        var StrList = new List<string>(pStrEnum);
        if (StrList.Count == 0) {
            return new long[0, 0];
        }

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

        SplitAct(StrList[0]);

        long UB_X = LongArr.GetUpperBound(0);
        long UB_Y = StrList.Count - 1;

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

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

#region PQueue_Arr
// 内部で配列使用の優先度付きキュー (根のValが最小)
internal class PQueue_Arr
{
    internal struct PQueueJyoutaiDef
    {
        internal long CurrX;
        internal long CurrY;
        internal long Val;
    }

    private PQueueJyoutaiDef[] mHeapArr;
    private long mHeapArrCnt = 0;

    // コンストラクタ
    internal PQueue_Arr()
    {
        mHeapArr = new PQueueJyoutaiDef[65535];
    }

    internal bool IsEmpty()
    {
        return mHeapArrCnt == 0;
    }

    internal long Count()
    {
        return mHeapArrCnt;
    }

    internal long Peek()
    {
        return mHeapArr[1].Val;
    }

    // エンキュー処理
    internal void Enqueue(PQueueJyoutaiDef pAddJyoutai)
    {
        long CurrNode = 1 + mHeapArrCnt;
        if (mHeapArr.GetUpperBound(0) < CurrNode) {
            ExtendArr();
        }

        mHeapArr[CurrNode] = pAddJyoutai;
        mHeapArrCnt++;

        while (1 < CurrNode && mHeapArr[CurrNode / 2].Val > mHeapArr[CurrNode].Val) {
            PQueueJyoutaiDef Swap = mHeapArr[CurrNode];
            mHeapArr[CurrNode] = mHeapArr[CurrNode / 2];
            mHeapArr[CurrNode / 2] = Swap;

            CurrNode /= 2;
        }
    }

    // 配列のExtend
    private void ExtendArr()
    {
        PQueueJyoutaiDef[] NewHeapArr = new PQueueJyoutaiDef[mHeapArrCnt * 2];
        mHeapArr.CopyTo(NewHeapArr, 0);
        mHeapArr = NewHeapArr;
    }

    // デキュー処理
    internal PQueueJyoutaiDef Dequeue()
    {
        PQueueJyoutaiDef TopNode = mHeapArr[1];
        long LastNode = mHeapArrCnt;
        mHeapArr[1] = mHeapArr[LastNode];
        mHeapArrCnt--;

        MinHeapify(1);
        return TopNode;
    }

    // 根ノードを指定し、根から葉へヒープ構築
    private void MinHeapify(long pRootNode)
    {
        if (mHeapArrCnt <= 1) {
            return;
        }

        long Left = pRootNode * 2;
        long Right = pRootNode * 2 + 1;

        // 左の子、自分、右の子で値が最小のノードを選ぶ
        long Smallest = mHeapArr[pRootNode].Val;
        long SmallestNode = pRootNode;

        if (Left <= mHeapArrCnt && mHeapArr[Left].Val < Smallest) {
            Smallest = mHeapArr[Left].Val;
            SmallestNode = Left;
        }
        if (Right <= mHeapArrCnt && mHeapArr[Right].Val < Smallest) {
            Smallest = mHeapArr[Right].Val;
            SmallestNode = Right;
        }

        // 子ノードのほうが小さい場合
        if (SmallestNode != pRootNode) {
            PQueueJyoutaiDef Swap = mHeapArr[SmallestNode];
            mHeapArr[SmallestNode] = mHeapArr[pRootNode];
            mHeapArr[pRootNode] = Swap;

            // 再帰的に呼び出し
            MinHeapify(SmallestNode);
        }
    }
}
#endregion

解説